Euro cylinder measuring guide showing how to measure side A and side B from the central fixing screw to determine the correct cylinder size for your door

Not sure which size cylinder you need?

Euro cylinders are measured in two halves, separated by the central fixing screw. Take both measurements from your existing cylinder before ordering, and match them to the size listed above.

A — Internal side
Measure from the centre of the fixing screw to the outer edge of the cylinder on the side that faces inside your home. Common sizes are 30mm, 35mm, 40mm, 45mm, or 50mm.

B — External side
Measure from the centre of the fixing screw to the outer edge of the cylinder on the side that faces outside your home. Common sizes are 30mm, 35mm, 40mm, or 45mm.

Cylinders are typically described as A/B — for example, a 35/45 cylinder has 35mm on the internal side and 45mm on the external side. Get both measurements right and the cylinder will fit your door perfectly.

Still unsure? Send a photo of your existing cylinder to info@homesecureshop.co.uk and we'll match it for you — or call 0151 521 8089 to speak to our team.

Full measuring guide

Which lock is right for your door?

All four fit standard uPVC and composite doors. Swipe to compare →

Compare locks
Our recommendation Avocet ABS 4.98 (49) Rated 4.98 out of 5 from 49 reviews £44.99Trusted and fitted by us for over 10 yearsView
Apecs AP1 review£54.99Top ratings from a newer brandYou're viewing this
Yale Platinum 4.63 (76) Rated 4.63 out of 5 from 76 reviews From £29.99A household name at a great priceView
Standard V5No reviews yet£9.99Budget or internal doorsView
Anti-snap ratingTS007 — what insurers ask for★★★ 3-star★★★ 3-star★★★ 3-starNot rated
Sold SecureIndependent attack testDiamondDiamondNot listed by YaleNot rated
If it's snappedHidden cam locks — door stays shutFront snaps off, cam stays lockedFront snaps off at a set pointNot tested
Key copiesOnly by approved dealers, with your key cardCut to codeKey code on ID cardAny key cutter
One key for all doors✓ YesNot availableNot availableNot available
Guarantee5 yrs + £2,000 snap cover10 yrs + £2,500 break-in cover10 yrs + £3,000 snap coverNone stated

Ratings and guarantees as published by each manufacturer. Snap and break-in cover must be registered with the manufacturer. Reviews are from Home Secure customers.

Product overview

Two top accreditations. One cylinder. The APECS AP holds both the BSI 3-Star Kitemark (TS007) and Sold Secure Diamond — the two highest security ratings a euro cylinder can earn — protecting against snapping, drilling, picking, bumping and plug extraction with no add-on security handles or guards needed.

What sets the AP apart is what happens during an attack. A sacrificial point breaks away and a patented interlocking cam mechanism locks down the internal parts — the intruder gets nowhere, and crucially, you can still unlock the door from inside and exit safely. On thumbturn versions, a dedicated release button provides this escape function.

  • Dual accredited — BSI 3-Star Kitemark (KM621947) and Sold Secure Diamond (CLME08161454), tested to TS007:2014 and EN1303:2015
  • Attack-resistant throughout — anti-pick, anti-bump and anti-drill pins in brass and hardened carbon steel, with a dimple/slider hybrid key and over 180,000 key combinations
  • £2,500 break-in guarantee — if a snapping attack on this cylinder ever succeeds, APECS pays up to £2,500 towards uninsured losses
  • 3 high-security keys included — copies cut to code only, so your keys stay under your control
  • Key-key or thumbturn, in Brushed Satin Nickel or Brushed Brass, sizes from 70mm to 110mm including offsets
  • Guaranteed for 10 years (5-year snap-secure guarantee)

A straight swap for your existing euro cylinder — no drilling and no door modifications. Measure both sides of your current cylinder to the centre screw before ordering.

Delivery & Returns

How much is delivery?

UK Mainland Delivery is £2.99 on all items no matter how many you order!

Northern Ireland, Scottish Highlands, Channel Islands £6.00.

We do not offer International Delivery (Ireland, France, Spain etc).

When will my order be dispatched?

Orders before 2pm (Monday to Friday) are usually dispatched same day but may take up to 24 hours.

When will I receive my item?

We ship on 2 working day courier. Fully Tracked. Tracking will be emailed on dispatch.

Special order items such as keyed alike locks will take longer to dispatch. Please refer to product description for lead times.

I haven't received my item?

Please email us your name, order number and date of purchase.

We prefer email as it allows us time to research and respond.

Returns Information

We operate a 30 day refunds and return policy.

If you change your mind you must return the product back to us within 30 days of delivery

Please include a copy of your invoice and a note stating reason for return.

Additional keys, locks keyed alike or built to code are non refundable as they are personalised made to order goods.

Any refund, which is due to a fault or other defect, will include a refund of the applicable delivery charges otherwise not.

It is the buyers responsibility to arrange the return of goods to us. We do not offer a collection service for returning items.

Items must be returned including original product packaging and accessories.

We reserve the right to refuse any returns that do not comply with this policy.

Please post returns to the following address:

Home Secure (Online)

Unit 5, Brookfield Drive

Liverpool, L9 7AJ

United Kingdom

Frequently Asked Questions

Yes — it holds the BSI 3-Star Kitemark (KM621947) under TS007 and is additionally Sold Secure Diamond accredited, the highest independent security standard for euro cylinders. It needs no extra security handles or cylinder guards to achieve this rating.

The cylinder breaks at a sacrificial point and a patented interlocking mechanism locks the internals, blocking any further attack. Unlike many anti-snap cylinders, the AP remains operable from the inside afterwards, so you can still exit your home.

If the external side has been snapped in an attack, pressing the button lets you operate the lock from inside and exit the property — the escape function that keys provide on key-key versions.

In the unlikely event a break-in succeeds through a snapping attack on the AP cylinder, APECS pays up to £2,500 towards losses not covered by your home insurance.

Each cylinder comes with 3 dimple/slider hybrid keys. Copies can only be cut to code through authorised centres, so lent-out keys can't be duplicated without your knowledge.