What is a Door Cylinder Lock?
A door cylinder lock, often called a cylinder lock, revolves around a central cylinder. This cylinder interacts directly with your key. When you insert and turn your key, the cylinder activates, either locking or unlocking the door. This mechanism ensures you can secure your home effectively and easily.

Rockdoor Lock
This Rockdoor lock comes with three keys in purple. You can also purchase extra Rockdoor keys if you need more. This is sourced directly from Rockdoor, ensuring perfect compatibility and reliability.
Keyed Alike only comes Key / Key. Thumb turn is currently not available.
Why Upgrade Your Cylinder Lock?
Upgrading the lock on your door is an effective and relatively affordable way to enhance security. You can replace the cylinder lock on many doors, including uPVC doors like French doors, or composite doors such as front and back doors.
Modern locks offer keyed alike sets for one, two, or even three or more locks. You can get them with three keys, and some come with five keys. Additionally, some locks come with cards and special numbers so you can order a new lock to match your existing locks.
Upgrading your lock is easy and will typically cost anywhere from £50 to £60, depending on the lock, the number of keys, and whether you want it keyed alike or matched to your existing locks.
If you are looking for a new lock, we offer a 3 star Avocet ATK lock with three branded Rockdoor keys.


What makes a lock so secure?
Modern high-security door cylinders, such as the Avocet ABS, Ultion Lock, and Yale Platinum, use cutting-edge technology and robust materials such as molybdenum to provide elevated home security. Here are some key features that make these locks so secure:
Anti-Pick
Anti-pick locks are engineered with intricate pin configurations and unique features that make them extremely difficult to pick.
Increased Number of Pins
Higher pin counts offer vast key combinations, making them hard to pick or bump. For example, the Ultion lock has 11 pins. This contributes to Anti-pick technology.
Multiple Sacrificial Layers
Modern locks typically contain more than one sacrificial layer. These break off during an attack to protect the core of the cylinder. This is also known as Anti-snap.
Internal Strength
Modern locks are crafted from robust materials, such as Molybdenum. These locks resist forceful attacks and help resist drilling a lock.
Magnetic and Dimple Key Technology
You may wonder why some keys are flat and have dimples. Well these keys provide higher key control and are harder to pick and copy.

What is the Best Lock?
As composite door installers, we have dealt with a lot of locks over the years. There are 3 popular brands that promise top security. Here’s a detailed look at three popular choices:
Each of these locks has unique features and benefits, helping you find the perfect fit for your home security needs.
Avocet ABS Lock
Certification
Holds the TS007 3-star rating and the superior SS312 Diamond grade, marking it as exceptionally secure.
Design
Available in Polished Silver or Polished Gold finishes.
Features
Anti-pick, anti-drill, anti-snap, anti-bump. Can come with a thumbturn. Flat magnetic dimple keys. Can be keyed alike.
Size Range
Offers compatibility with a wide range of door thicknesses, making it a versatile choice for various types of doors. Will be suitable for most uPVC and composite doors.
Ultion Plus Lock
Certification
Boasts the TS007 3-star certification, ensuring high security.
Design
Comes in either Silver or Gold, with the UK’s thickest key design for added strength and security. Getting keys cut can be difficult.
Features
Anti-pick, anti-drill, anti-snap, anti-bump. Can come with a thumbturn. Flat dimple keys. Features 11 pins which is a lot higher than the standard 6 pins in most locks.
Size Range
Not as versatile as the Avocet ABS when it comes to sizes, but offers robust security options. Could be harder to purchase than an Avocet or Yale Platinum as less places sell them.
Yale Platinum Lock
Certification
Features the TS007 3-star rating.
Design
Available in Silver or Gold.
Features
Anti-pick, anti-drill, anti-snap, anti-bump. Can come with a thumbturn. Flat dimple keys.
Size Range
Very good size options, compatible with most doors.
Conclusion
Avocet ABS, Ultion Plus Lock, and Yale Platinum represent the top tier of door security, each boasting the TS007 3-star certification.
They all offer standard protections for anti-snap, anti-pick, anti-drill and anti-bump.
Avocet ABS distinguishes itself further with an SS312 Diamond grade certification, marking it as the premium option for enhanced security. All three brands offer designs in Silver or Gold and feature internal thumb turns for ease of use.
The Avocet ABS and Yale Platinum offer the best compatibility with various door thicknesses, and Ultion Plus Lock’s key thickness is also something that is overlooked but very useful.
Ultimately, the choice between these locks will depend on individual security needs and aesthetic preferences.
If I was buying a lock today, I would choose the Avocet ABS due to its ease of purchase, wider compatibility with doors, mid-range pricing and excellent security features.
Read our guide on how to measure and change your door lock.
Frequently Asked Questions
Ultion offer the thickest key, Avocet hold the highest security accreditation and Yale offers the best size options
All three locks are very good, but the Avocet stands out for its higher SS312 Diamond grade certification
Yes you can, see our published guide on how to measure and remove a lock
All three brands are highly durable and built to withstand wear and attacks.
Ultion locks feature a unique lock-down mode that activates during an attack, providing unmatched security.
Yes, Avocet locks are designed to resist picking, drilling, bumping and snapping.
Look for locks with a 3-star rating or certification from recognised security standards such as SS312 or TS007
The composite doors we supply and fit use Avocet locks. These are reliable and secure locks.
Yes. If you would like keyed alike 3-star locks, we recommend Avocet ABS.
Anti-snap technology prevents burglars from snapping the lock cylinder to gain entry.
Yes, all of these locks are suitable for various types of doors, including patio doors.
Absolutely. Ultion, Avocet, and Yale locks are suitable for uPVC doors.
You can buy these locks yourself for around £45 to £60 per lock and fit them yourself. We recommend Avocet ABS as they are easy to purchase.