How to find the right locking cylinder


 Profile cylinders are among the best-known and most frequently used locking cylinders. Whether flat key or reversible key, emergency function, knob cylinder or double cylinder: here you can find out more about locking cylinders and their properties.

How to find the right locking cylinder

Lock cylinder: Overview

The most common locking cylinder in the United States is the profile cylinder.

Profile double cylinder: the classic

Profile double cylinder

The double cylinder is one of the most common profile cylinders. It has 6 pins and protection against drilling and breaking. It has a nickel coating and is usually supplied with 5 keys. These are either flat or reversible keys.

Cylinder lock: structure

Cylinder locks can be made of different materials, have different lengths and, above all, work with different types of keys and mechanisms, which are often manufacturer-specific. These include:
  • classic profile cylinders,
  • cylinders with emergency and danger functions,
  • knob cylinders,
  • half cylinders.

Standards and burglary protection

A cylinder lock can have several security systems that protect your lock against burglary. These include picking protection, drilling protection, break-in protection and copy protection. Other types of cylinders are now hardly used in Germany, e.g. round cylinders.

Norms and standards

In Europe, locking cylinders must comply with the DIN EN 1303 standard in order to be considered secure against locking and break-in. There is also the Europe-wide SKG standard, which divides locking cylinders into two classes.

Determine the length of a cylinder

cylinder lock

If you want to replace your lock cylinder, the most important feature is its length (in mm). The cylinder consists of a keyhole on each side and a locking lug in the middle, which - operated by the key - carries out the locking. To determine the length, the distance from the centre of this locking lug (cylinder centre) to the keyhole must be determined. The vast majority of cylinders measure 60 mm (total length). The total length is often given in the description as 30/30 because each side measures 30 mm from the centre of the locking lug to the keyhole. However, several variants are possible:
  • 30/30
  • 30/40
  • 40/40
  • 40/50
  • etc.
The reference points are always the cylinder centre and the keyhole. This criterion is crucial for replacing your locking cylinder.
 When there is no key in the cylinder, the locking lug is usually at 7 o'clock (clock face) when viewed from the front. In rare cases, it can be at 3, 9 or 12 o'clock. Some cylinders have an adjustable locking lug.

Keys and locking cylinders: structure and security

Depending on the type of cylinder, the key may have notches, dimples, bumps or depressions. The profile of your key may be cross-shaped or star-shaped, but is usually flat, and milled on one or two sides. The combination of profile and notches or depressions determines the "code" needed to operate the pins inside the cylinder and block the locking lug. The right profile allows the key to be inserted into the cylinder - the right notches can turn and lock it! The more pins the profile cylinder has, the harder it is to tamper with. Expect 5 to 36 pins for a cylinder.

Key species

How to find the right locking cylinder

The right keys can increase the complexity of the cylinder when it is replaced, thereby increasing the security of the lock. The key is therefore an indication of the complexity of the cylinder:

  • A flat or notched key with millings on one side of the shaft is the standard. It is found on almost every bunch of keys.
  • A flat or notched key with millings on both sides offers a little more security because it indicates a cylinder with more pins.
  • A paracentric key is similar to a flat key. However, it has a key profile that overlaps the centre to offer better protection against break-ins.
  • A reversible key has dimples instead of notches. It fits into the lock cylinder on both sides.
  • Some manufacturers offer special security keys.

Have keys copied

door latch key

The number of keys sold with the locking cylinder varies - often 3 to 5 keys are included. Depending on the type, the key can be copied more or less easily. Flat keys can be duplicated at any locksmith. For paracentric keys and reversible keys, you usually have to contact the manufacturer directly.

Copy-protected keys and warranty

Some keys are copy-protected or require a card supplied with the cylinder to copy the keys. Attention, keys with a lifetime guarantee can only be copied at the factory: remember the delivery times!

Complexity of the locking system = security of a cylinder?

Depending on the type of security lock, it is more or less easy to break open a cylinder lock.
It is also possible to drill through a cylinder to destroy the pins or to break it open with a hammer from the outside. 
A protective fitting can help here. It prevents the cylinder from being drilled open. Breaking open is made even more difficult if the locking cylinder is made of a durable alloy that can withstand blows. Under no circumstances should the cylinder protrude from the door. It must sit flush to prevent it from being pulled from the outside.

Burglar protection for cylinder locks

A cylinder should be protected against the following burglary techniques:
  • Pulling - using pliers. This is prevented by flush installation. 
  • Breaking - using hammer blows. This is prevented by a durable alloy. 
  • Drilling - using a drill. This is prevented by a protective fitting. 
  • Lock picking - using special tools. The more pins a cylinder has, the harder it is to crack. 
  • Key copying. A security card prevents duplication. 
  • Bumping - using a bump key. This is prevented by reinforcements and a protective fitting.

The SKG test mark under the magnifying glass

The SKG test mark is a Europe-wide standard that says something about the security of a cylinder lock.

Lock cylinder



Cylinder with drilling and pulling protection from both sides


Drilling protection, impact protection and core pulling protection

Locking cylinder types: half cylinder, freewheel cylinder, knob cylinder, etc.

cylinder latch types

Double cylinder

The keys can be inserted on both sides. However, locking or unlocking is only possible with one of the two keys.

Half cylinder

These cylinders are especially suitable for garage doors. They only have one key entry. Their dimensions are 30/10 mm.

Cylinder with hazard function

This function has different names depending on the manufacturer. With this type of cylinder lock, a key inserted on one side does not prevent the door from being unlocked or locked from the other side. This system is particularly practical when several people live in one household. With classic profile cylinders, the door cannot be unlocked from one side if a key is inserted on the other side.

Knob cylinder

This locking cylinder can be opened from the inside with a knob.

Locking cylinders for French doors

When buying small locks for windows and doors, you should be careful: the locking nose of these cylinders is smaller. If you can't find the model you want, file the locking nose so that it doesn't get stuck in the lock!

Locking mechanisms of a cylinder

Locking cylinder with pins

Lock cylinders with pins are the most common. The more pins there are, the more security there is. The majority of cylinders have 6 pins. 
A cylinder with anti-picking protection is ideal. Pins made of nickel silver (a durable alloy) are the most secure. Depending on the arrangement of the pins, it can be difficult to duplicate the key.

Locking cylinder with rotating discs

This mechanism prevents the lock from being drilled open. This makes breaking in using a drill almost impossible.

Locking cylinder with discs

In everyday life, there is no reason to equip your door with such a mechanism. This is a high-security lock.

Bramah Castle

Such a lock is rarely used for front doors these days.

One key for several locking cylinders – is that possible?

For this, you need so-called keyed-like cylinders. These profile cylinders can all be opened with the same key, which makes your key ring lighter! The locking cylinders can be of different types.

Profile cylinder: Conclusion

Replacing a cylinder is quite simple. It is only held in place by a screw that is accessible from the edge of the door where the lock is located. Unscrew this after removing the locking lug and then simply pull the cylinder out.
A cylinder lock only protects doors that are sturdy. There is no need to buy a high-security lock if your door is made of cardboard and can be easily pushed in. The strike plate, under which the locking lug is located, is also an important security aspect. It must be firmly and properly attached.

To choose the right cylinder lock, you should pay attention to the following:
  • the currently installed model you want to replace; 
  • its size; 
  • its type; 
  • various protection measures; t
  • he type of key.
And feel free to use lubricant if your lock is stuck!

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