DOM lock cylinder: what to check before you pay

Updated: October 2026

You are about to spend about £431.56 to £498.49 on a DOM lock cylinder from amazon.co.uk, and the title will not tell you whether it turns the lock.

You are about to spend about £431.56 to £498.49 on a DOM lock cylinder from amazon.co.uk, and the title will not tell you whether it turns the lock. In this set a DOM lock cylinder is a euro-profile Diamant barrel, not a rim nightlatch and not a British oval cylinder. Check the profile, both sides from the fixing screw, the cam, and whether you need a restricted key or a TS 007 mark. The three listings are on the DOM lock cylinder comparison. Peter F. checked those UK listings in October 2026. Nobody fitted these cylinders in a lab. A qualifying purchase can earn a commission at no extra cost to you.

Our top picks

Badge	Product	Size	Cam	Keys	Note	Price	Offer
Best overall	DOM DOM long-cam cylinder 30 x 40 mm	30 x 40 mm	Long cam	5 keys	6.6	about £451.89	View offer
Best value	DOM DOM Diamant cylinder 30 x 30 mm	30 x 30 mm	n/a	5 keys	6.2	about £431.56	View offer
	DOM DOM Diamant nickel cylinder 30 x 30 mm	30 x 30 mm	CAM LG	Key(s)	4.8	about £498.49	View offer

Best overall

DOM DOM long-cam cylinder 30 x 40 mm

6.6/10about £451.89

View offer

Best value

DOM DOM Diamant cylinder 30 x 30 mm

6.2/10about £431.56

View offer

Rank 3

DOM DOM Diamant nickel cylinder 30 x 30 mm

4.8/10about £498.49

View offer

On this page

1.What a DOM lock cylinder is
2.Size and cam before price
3.Key control and what the listing does not say
4.When to skip DOM for this door
5.Order only when four facts match

What a DOM lock cylinder is

The three listings are Diamant euro cylinders: polished 30 x 30 mm at about £431.56, brass long-cam 30 x 40 mm at about £451.89, and nickel 30 x 30 mm at about £498.49. None has a star rating. A euro cylinder sits in a multipoint lock, held by one screw on the door edge. These listings will not replace a British oval cylinder or a rim nightlatch. Diamant is DOM's disc system. The double-cylinder page publishes EN 1303:2015 code 160B0C6D and marks anti-snap as No. Two titles begin 333TDIA. The amazon text does not spell out what that code does.

Size and cam before price

Write the size as outside/inside from the centre of the fixing screw, not from the cam. A 30/30 is 60 mm. The nickel listing states that. The polished listing does not. A 30/40 is 70 mm, which the long-cam listing states, and it is not 35/35. The two measurements are on how to fit a euro cylinder. West Yorkshire Police say the cylinder must not protrude. About 3 mm past the handle is the limit fitters use. Only the listing at about £451.89 states a long cam. The polished cam is blank. The nickel title says CAM LG, kept as written. If you cannot see the old cam, use a locksmith.

Testsieger

DOM DOM long-cam cylinder 30 x 40 mm

6.6/10about £451.89

View offer

Key control and what the listing does not say

A high-street booth should not copy a restricted DOM key, and only while you still have the security card. These listings do not say a card is in the box, or that they join keys you already hold. Three orders are not a master-key system. Diamond in the title is Diamant, not Sold Secure and not TS 007. DOM marks anti-snap as No. AC Leigh lists rs Sirius as the TS 007 3-star DOM cylinder. Two listings name five keys. The nickel listing says key(s). Do not merge that with a manufacturer note of three keys.

When to skip DOM for this door

Skip this set when the job is snap resistance on a uPVC or composite street door. West Yorkshire Police describe a 3-star TS 007 cylinder, or a 1-star cylinder with a 2-star handle. SS312 is a separate certificate. That choice is on DOM cylinder vs TS 007. Approved Document Q applies to new dwellings in England, not as a retrofit order. An insurer can still name a mark. Also leave the set for a fire door, a communal door, a match to keys you already hold, or a lost security card. The replacement card goes through the dealer. Call a locksmith when the cam is unknown or the fixing screw has sheared.

Order only when four facts match

Order only when the profile is euro, the split matches the tape, you can see the cam, and you do not need a star mark. The top pick is the long-cam 30/40 at about £451.89. The best value is the polished 30/30 at about £431.56 after you have checked the cam.

Common questions

Will this replace the cylinder in my uPVC door?

It can, if that door already uses a euro cylinder and you match both sides and the cam. Many uPVC and composite doors use a euro barrel in a multipoint lock. A British oval profile will not accept these listings, and a rim nightlatch will not either. If the old cylinder sits proud of the handle, a like-for-like length keeps that exposure.

Is 30/30 a normal UK front-door size?

It is a real size, and it was the minority in one retailer's TS 007 mix. Home Secure Shop reported 30/30 at about 4 percent, with 35/35 first. Your door might still be 30/30. The check is the tape: 30 mm and 30 mm is 60 mm overall. The nickel listing states 60 mm. The polished listing does not, so confirm the old cylinder before you trust the title.

What is a long cam, and do I have one?

The cam throws the lock when you turn the key. A long cam reaches a different case from a standard cam. Only the brass listing at about £451.89 states long cam, at 30 x 40 mm and 70 mm overall. If the old cam is a short bar, that listing is the wrong part. If you cannot withdraw the old cylinder, do not guess from the title.

Can a high-street shop copy a DOM key?

Not if the key is on a restricted DOM system. Those keys are cut by a dealer against the security card. These amazon listings do not say the card is included, so five keys in a title is not proof you can add another door later. A kiosk that offers to copy any key is a reason to leave. If the card is already lost, the replacement route is the dealer, not a fresh order of a different size.

Will this fit a Yale rim nightlatch?

No. A rim nightlatch uses a rim cylinder on the face of the door. These three listings are euro-profile Diamant cylinders. The shape will not enter the nightlatch, and the cam is meant for a euro lock case. If the only lock on the door is a surface nightlatch, you are in a different category. Compare the profile before you compare the three prices.

DOM Diamant or ix Twido