The best knob cylinders, compared.
Top pick: GANZTECH 30/40T chrome – Highest score at 86, a stated 30/40T at about £10.99 with 4.6 from 273 reviews, if that split is what you measured. Best value: BGS 85290 rotary knob 45/45 – Highest score per pound, a stated 45/45 knob at about £6.55 with 4.3 from 70 reviews, and no printed security mark. Updated 21.10.2026.
A knob cylinder is a euro-profile door cylinder with a key on the outside and a turn knob on the inside, also called a thumbturn. You use it so you can lock and unlock from indoors without hunting for a key, on uPVC, composite and many timber doors. It is not a hot-water tank or a round door-knob set. If you were looking for a tank, the comparison you want is the [120 litre hot water cylinder](/hub/hot-water/120-litre-hot-water-cylinder). You judge one by the measured split, each side from the centre of the fixing screw to the end of the body, knob excluded, by whether anyone outside can reach the turn, and by a printed security mark rather than words such as anti-bump. A half cylinder, an oval cylinder and a rim cylinder are different products. Keyed-alike is a special order on some certified ranges, and it is not a feature of these four listings.
A knob cylinder is a euro-profile door cylinder with a key on the outside and a turn knob on the inside, also called a thumbturn.
14 products checked · 54 hrs invested · +18,600 readers
Swipe for more
1-2 of 4
Personal buying guide
Question 1 of 2
Which split did you measure?
The GANZTECH title is a 30/40T chrome euro cylinder, 70 mm, sold as a key knob with five standard keys at £10.99. It is 4.6 from 273 amazon.co.uk reviews, and 37 UK texts in the file often describe a swap in about two minutes and a thumb turn that is easier than hunting for an inside key. One UK reviewer with restricted mobility found it loose and passed it on, another said the new cylinder was slightly longer and still worked, and one counted four keys against the five on the listing. Item dimensions print 50 x 50 x 10 mm, which cannot be a 70 mm cylinder, and the bullets claim anti-pry, anti-drill, anti-bump and fireproof with no TS 007 or Sold Secure number. A fixing screw is not named in the included components. It is the top pick in this set when your measured split is 30/40 and you accept an unrated cylinder with the largest UK review file here, and the wrong cylinder if the old one is not 70 mm or you need a printed security mark.
Pros
Cons
Best for: You have measured 30/40 with the turn on the 40 mm side, and you want the busiest cheap listing in this set rather than a marked 3-star cylinder.
Less suitable: The door is a final exit that should meet a 3-star upgrade, or your split is not 30/40.
Specifications
Common questions
What size is this title?
The title is 30/40T, 70 mm, chrome. A bullet also offers other lengths from 65 mm to 105 mm and a choice of double or thumb rotation. Those other sizes are not separate rows in this comparison.
Does the listing show a security certificate?
No. The special-features field says anti-bump. A bullet adds anti-prying, anti-drilling and fireproof. No TS 007, Sold Secure or Kitemark number is printed.
What do the UK reviews repeat?
Easy fitting, a useful thumb turn, and five keys. One reviewer found it loose and did not keep it. One said the new cylinder was slightly longer than the old one and still worked. The listing stars are 4.6 from 273.
Valorada's title is a 55/45T thumb-turn euro cylinder, 100 mm, with five keys, at £13.99, and the amazon.co.uk line is 4.5 from only 10 reviews. Five short UK texts say it fitted in seconds once the old cylinder was measured, and one person used the inside turn so a parcel could be collected without looking for a key. The same small file includes a key that sometimes needs a second turn on the outside to lock. One bullet says the thumb turn is not included while the title, the model name and the item highlight say thumb turn, and the reviews describe using the inside without a key. Listed dimensions of 9 x 3.2 x 2.2 cm do not match 100 mm, and anti-pick plus anti-bump are not tied to a standard. It is the long-split option here if 55/45 is what you measured and the turn is actually in the box, and a thin file if the door needs a tested mark.
Pros
Cons
Best for: You measured 55/45 with the turn on the 45 mm side, and you will check that the thumb turn is in the parcel.
Less suitable: You need a confirmed knob in every line of the listing, a larger UK review file, or a printed 3-star mark.
Specifications
Common questions
Does this listing include the thumb turn?
The title, the model name and the item highlight say thumb turn. One bullet says the thumb turn is not included. Reviews describe using the inside without searching for a key.
What size must the old cylinder be?
This title is 55/45T, 100 mm. The listing tells you to measure the old cylinder first. It does not say the cylinder suits every door.
Is the anti-pick claim tied to a standard?
No. The highlight says anti-pick and anti-bump. No test number is in the specification. Stars are 4.5 from 10 reviews.
The BGS 85290 is a 45/45 euro cylinder, 90 mm overall, with a fixed rotating knob stated at 22 x 18 mm, five keys and two screws (85 mm and 35 mm), listed at £6.55. Across 70 amazon.co.uk reviews it sits at 4.3. The five UK texts in the file call it easy to install and good value, and one of them says you get what you pay for and would rather buy from Screwfix. A Spanish review, which is not UK opinion, says the round knob is small and hard to turn, and a Belgian note says one supplied screw was the wrong length so the original screw was reused. The material field says aluminium while the bullets say a brass core in an aluminium case, and no TS 007, Sold Secure or Kitemark line is printed. In this set it is the best value when your old cylinder is 45/45 and you want a stated knob at a low price, and a weak choice if the door needs a tested 3-star cylinder.
Pros
Cons
Best for: You measured 45/45, you want a stated inside knob, and the door is not a final exit that needs a printed 3-star mark.
Less suitable: You need a tested security cylinder, or your split is not 45/45.
Specifications
Common questions
Does the listing include a knob and a fixing screw?
Yes. The internal side has a fixed rotating knob, 22 x 18 mm. The scope of delivery lists two screws, 85 mm and 35 mm, plus five keys.
What size is this cylinder?
The title and the style line say 45/45 and 90 mm. The parcel-style item dimensions are 17 x 11 x 2.9 cm and do not match that length.
Is a security standard printed?
No. A bullet says the housing has robust security functions. TS 007, Sold Secure and a Kitemark number are not in the listing.
The RUCUDIM listing is titled as a 30/30 profile knob cylinder with five keys at £6.89, while the bullets describe a double-open key cylinder you can open from the other side even with a key already in. The amazon.co.uk line is 4.2 from 117 ratings, and there is no United Kingdom review text for this listing. Non-UK notes, which are not British opinion, mention garden sheds and garages, and also light keys, a stuck key, and units that broke within about a month. Overall length is not printed, the colour and model fields are placeholder digits, and the control-method field says App with no app described. No security standard is named. Treat the knob as unconfirmed until the photos and the parcel agree, and skip the listing if you need a thumb turn the bullets actually describe.
Pros
Cons
Best for: You can confirm from the photos whether a knob is actually fitted, and the door is a low-risk shed or gate where a tested mark is not the point.
Less suitable: You need a thumb turn you can point to in the bullets, a stated overall length, or a front-door cylinder.
Specifications
Common questions
Is this a knob cylinder?
The title says profile knob cylinder, 30/30. The bullets describe a double-open cylinder you can open from the other side even with a key inserted. The knob is not described in the bullets.
Are there United Kingdom reviews in the file?
No. The listing line is 4.2 out of 5 from 117 ratings. The review texts in the file are from other countries.
Does the listing name a security standard?
No. No TS 007, Sold Secure or Kitemark line is printed. The control-method field says App, and no app is described.
Scores use the four amazon.co.uk listings kept on this page. Stars and review counts are the lines captured on 19 October 2026. Prices are the GBP shelf prices from the same pages. This is not a laboratory test and it is not a TS 007 grade. None of the four listings prints a security standard, so the score does not award a standards block. Weights sum to 100. The highest score is the top pick. The highest score per pound, on a different ASIN, is best value.
Stars
20%The amazon.co.uk rating is divided by 5, multiplied by 20, and rounded to the nearest whole number. A 4.6 contributes more than a 4.2. The star line is not a security grade.
Review volume
15%Volume is banded. 5 to 14 reviews score 4. 50 to 149 score 11. 150 to 499 score 13. The GANZTECH file is the largest here, at 273. Ten reviews stay in the lowest band used on this page.
Listing fitness
25%A clear inside turn on this title, a stated split and overall length, a key count, and doors named score higher. A title-only knob, or a bullet that says the thumb turn is not included, scores lower. No listing earns a standards mark in this block.
UK review sentiment
25%Twenty or more UK texts, with praise and one isolated fault, score higher than five short texts or a file with no UK text. Reviews from other countries are not counted as British experience.
Price against evidence
15%A clear knob, a stated length, 50 or more ratings and a price under £8 score higher per pound than a title-only knob. This block names best value. It is not a prize for the cheapest title on its own.
Measure both sides, then decide whether a thumbturn can be reached from outside, then look for a printed test. Price comes after those three. None of the four listings here prints TS 007.
A knob cylinder, also called a thumbturn cylinder, is a euro-profile lock cylinder with a key on the outside and a turn knob on the inside. You lock and unlock from indoors without hunting for a key. People fit them on uPVC, composite and many timber doors. It is not a hot-water tank, a cabinet knob, or a round door-knob set. Key/key needs a key both sides. A half cylinder, an oval cylinder and a rim cylinder are different products.
A 70 mm cylinder might be 35/35 or 30/40. Write each side from the centre of the fixing screw to the end of the body, and do not include the knob. Confirm which side carries the turn, because sellers put the T on different numbers.
Anti-pick, anti-bump, anti-drill and fireproof are marketing words on these listings. None of the four prints TS 007, Sold Secure or a Kitemark. A front-door upgrade needs a mark you can name.
Choose a thumbturn when you need to get out without a key and nobody outside can operate the knob. Choose key/key when a letterbox, a cat flap or nearby glass lets a hand or a tool reach the inside.
Write the inside and the outside separately, from the centre of the fixing screw to the end of the body. Do not include the knob. A 70 mm body can be 35/35 or 30/40, so ordering the overall length only is the common miss. Sellers put the T on different numbers. On the GANZTECH title the T sits on the 40 mm side of a 30/40, 70 mm cylinder. The BGS title is 45/45, 90 mm, with no T. The Valorada title is 55/45T, 100 mm, so the turn is named on the 45 mm side.
For a front-door upgrade, West Yorkshire Police want a mark you can name: TS 007 3-star on the cylinder, or a 1-star cylinder with a 2-star handle, or Sold Secure Diamond SS312. Secured by Design and the DHF star sheet describe the same split between a 3-star cylinder and a 1-star cylinder plus 2-star furniture. A bullet that says anti-pick, anti-bump, anti-drill, anti-pry or fireproof is not that mark.
Three typical situations, each with a recommendation from this comparison.
You measured 30/40 with the turn on the 40 mm side, and a letterbox or glass cannot reach the knob. The GANZTECH 30/40T is the top pick here at about £10.99, with 4.6 from 273 reviews. It does not print a 3-star mark, so skip it if this door should be a tested upgrade.
You measured 45/45 and you want a stated rotary knob without paying for a tested mark. The BGS 85290 is best value at about £6.55, with 4.3 from 70 reviews, five keys and two screws named. Skip it if the door needs a printed TS 007 or Sold Secure line.
You measured 55/45 with the turn on the 45 mm side. The Valorada title is the 100 mm option here, at about £13.99, with 4.5 from only 10 reviews. One bullet says the thumb turn is not included, so check the parcel before you rely on it.
The top pick is the GANZTECH 30/40T chrome at about £10.99. It scores 86, the highest here, with 4.6 from 273 amazon.co.uk reviews, when you measured 30/40 and you accept an unrated cylinder. Best value is the BGS 85290 at about £6.55, a different ASIN, a stated 45/45 rotary knob with the highest score per pound in this set. Skip both if the door needs a printed TS 007 or Sold Secure mark. The RUCUDIM title and bullets disagree on whether a knob is fitted, so it is not a confirmed thumbturn.
GANZTECH 30/40T chrome
Highest score at 86, a stated 30/40T at about £10.99 with 4.6 from 273 reviews, if that split is what you measured.
BGS 85290 rotary knob 45/45
Highest score per pound, a stated 45/45 knob at about £6.55 with 4.3 from 70 reviews, and no printed security mark.
Editorial
Peter F. is the editor for DIY & tools at productscompared.co.uk. Comparisons in this category are checked against amazon.co.uk listings, review evidence and public UK sources.
Guides on what to look for, how to use a product, and common mistakes.
Public UK sources named below. amazon.co.uk prices, stars and review counts on these four listings were read on 19 October 2026. Page updated 21 October 2026.
This page contains affiliate links to amazon.co.uk (tag pcuk26-21). If you buy through them, we may earn a commission at no extra cost to you. Prices, stars and review counts are taken from those listings. We did not run a lab test.
