## Padlocks.

Systems and Suites

So far we've only been talking about individual padlocks in individual situations. The padlock on a gate for instance. But we need to go on now to look at padlocks in larger and more complicated situations.

Key Differs

Before we get stuck into the meat of keying systems and suites we need to understand what 'key differs' are.

Key differs are the total number of different bitting combinations that a pin tumbler cylinder can be fitted with, i.e. how many padlocks can be made that all have a different key?

To arrive at the total number of key differs there are for a particular padlock, you take the total number of different pins available and multiply that out by the number of pins in the cylinder So, for a 4 pin cylinder with 6 different sized pins available, the calculation is 6x6x6x6 = 1296 key differs.

In practice the number is actually lower than that because we don't use sequences such as 4 pins of the same size, or each one larger then the next etc.

To take an example the Kasp™ 125 series 50mm padlock with 5 pins has a total of 1988 potential key differs, where as the same series padlock in smaller size, 25mm, has only 4 pins and therefor only 202 possible key differs.

As you can see, the greater the number of pins, the greater the available number of key differs.

What if you had a building site with lots of different areas, each one locked with its own padlock and key? You'd have a pretty heavy pocket if you had to carry all of those around! That's why padlock manufacturers such as Kasp™ offer 'keyed alike' padlocks as well as Master suites and Grandmaster suites, all of which are explained in this section.