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Best DOM lock cylinder for a measured door

Updated: October 2026

You have three DOM titles on amazon.co.uk and you want the best DOM lock cylinder for the door you can measure. The useful difference is size and cam. The top pick is the long-cam 30/40 at about £451.89, only when the old cam is long and the split is 30 mm and 40 mm. The best value is the polished 30/30 at about £431.56, only when both sides are 30 mm and you do not need a stated TS 007 mark. Prices are on the [DOM lock cylinder comparison](/hub/door-and-window-security/dom-lock-cylinder). Peter F. compared the three UK listings in October 2026. This is not a lab test. A qualifying purchase can earn a commission at no extra cost to you.

You have three DOM titles on amazon.co.uk and you want the best DOM lock cylinder for the door you can measure. The useful difference is size and cam.

Our top picks

DOM DOM long-cam cylinder 30 x 40 mm

Best overall

DOM DOM long-cam cylinder 30 x 40 mm
6.6/10about £451.89
View offer
DOM DOM Diamant cylinder 30 x 30 mm

Best value

DOM DOM Diamant cylinder 30 x 30 mm
6.2/10about £431.56
View offer
DOM DOM Diamant nickel cylinder 30 x 30 mm

Rank 3

DOM DOM Diamant nickel cylinder 30 x 30 mm
4.8/10about £498.49
View offer
On this page
  1. 1.The three listings, side by side
  2. 2.If your cylinder is 30/30
  3. 3.If you need the long cam
  4. 4.Who should skip the set
  5. 5.Which listing to keep

The three listings, side by side

None of the three listings has a star rating, so the order follows fit. All three are DOM Diamant euro cylinders, and none prints TS 007 or Sold Secure. The polished listing is about £431.56, 30 x 30 mm, five keys, model 333TDIA0501, with cam and length blank. The brass listing is about £451.89, long cam, 30 x 40 mm, 70 mm, five keys. The nickel listing is about £498.49, 60 mm, 415 g, keys not numbered. What to collect first is on the DOM lock cylinder buying guide.

If your cylinder is 30/30

If both sides are 30 mm from the fixing screw, the length is 60 mm. The nickel listing states 60 mm. The polished listing does not, so measure first. A 35/35 door is 70 mm, and neither 30/30 listing is that split. The polished listing at about £431.56 is the best value, with five keys and model 333TDIA0501. The nickel listing costs about £66.93 more. Cut resistant is not a certificate, and CAM LG is not confirmed here as a long cam. Choose nickel only when you want that finish and you have checked the cam.
DOM DOM long-cam cylinder 30 x 40 mm

Testsieger

DOM DOM long-cam cylinder 30 x 40 mm
6.6/10about £451.89
View offer

If you need the long cam

The brass listing is the top pick, and the only one that states long cam: 30 mm and 40 mm, 70 mm overall, at about £451.89. Buy it when the old cylinder has that cam and that split. A long cam does not throw a standard case. A 35/35 door is also 70 mm and is still the wrong split. A 30/30 door is the wrong length and the wrong cam. It names five keys and brass, and it records a control method of App. A key cylinder does not use an app, so treat that as a catalogue error. The security-mark field is empty. About £451.89 does not buy a stated TS 007 mark. If the old cam is standard, leave this listing.

Who should skip the set

Skip all three if the street door needs snap resistance. West Yorkshire Police describe a TS 007 3-star cylinder, or a 1-star cylinder plus a 2-star handle, and they say the cylinder should not protrude. Sold Secure SS312 is a separate certificate. That argument is on DOM cylinder vs TS 007. Skip them for a rim nightlatch, for keys you already hold, for a lost security card, and for a fire door or a communal door. One key for several flats is a master-key design, not three Diamant orders. If the cam is unknown or the screw has sheared, measure with a locksmith first.

Which listing to keep

Keep the long-cam 30/40, the top pick at about £451.89, when the tape says 30 mm and 40 mm and the old cam is long. Keep the polished 30/30, the best value at about £431.56, when both sides are 30 mm and a stated 3-star mark is not the requirement. The nickel 30/30 at about £498.49 is the same nominal size without an extra certificate.

Common questions

Which of the three should I buy for a 60 mm cylinder?
A 60 mm euro cylinder is 30/30 when both sides are 30 mm from the fixing screw. The best value is the polished listing at about £431.56, if you accept an unstated cam and no TS 007 line. The nickel listing at about £498.49 is the one that prints 60 mm, without a certificate. The top pick is 70 mm and is the wrong length.
Is the £498 one more secure because it costs more?
The listings do not show that. It is the same nominal 30/30, with cut resistant as a feature line and no TS 007 or Sold Secure mark. Model number and key count are blank. The polished listing is about £66.93 less and names five keys and model 333TDIA0501. Spend the extra only after you have checked the cam, not because the price implies a higher grade.
When is the long-cam 30/40 the right one?
When the cylinder you remove has a long cam and measures 30 mm one side and 40 mm the other. That is the brass top pick at about £451.89, 70 mm overall, with five keys. It is the wrong part for a standard cam, a 30/30 door, or a 35/35 door that adds up to the same 70 mm. If you cannot see the cam, do not guess from the title.
Which one includes five keys?
The polished listing and the brass long-cam listing both say five keys. The nickel listing says key(s) and does not give a number. DOM's own configuration notes often say three keys. Those are different sources. Count the keys on the listing you buy, and do not add the manufacturer's three to the amazon five.
Should I skip all three?
Yes, if you need TS 007 or SS312, a rim cylinder, a British oval profile, a master-key suite, or a match to keys you already hold. Also yes if you have not measured both sides. No, if you have a euro door at 30/30 or a confirmed long-cam 30/40 and the job is the Diamant disc system rather than a star mark. The skip is about the job, not about the brand being poor.

Related pages

How to fit a euro cylinder

DOM lock cylinder

What to check before you order a DOM lock cylinder

DOM Diamant or ix Twido: which key you were quoted

DOM cylinder vs TS 007: skip Diamant for snap risk

Sources

Public UK and manufacturer sources, plus the amazon.co.uk listings B077Q4LF93, B08W4N7RSV and B077PSM71X. Figures are taken from those pages and from the digest. Checked for this comparison in October 2026.

  1. West Yorkshire Police, euro cylinder advice (retrieved October 2026)
  2. GOV.UK, Approved Document Q (retrieved October 2026)
  3. DOM Diamant double cylinder (retrieved October 2026)
  4. DOM ix Twido double cylinder, DOM-UK (retrieved October 2026)
  5. Hoppe, BS EN 1303 (retrieved October 2026)
  6. AC Leigh, DOM master-key cylinders (retrieved October 2026)
  7. Lock and Key, how to measure a euro cylinder (retrieved October 2026)
  8. amazon.co.uk listings B077Q4LF93, B08W4N7RSV and B077PSM71X (retrieved October 2026)