You want your masterkey system to last. It's an investment, and you need that investment to pay dividends for years to come. With a common pin tumbler lock, your system expansion is limited by the number of mathematic possibilities that are available. Those mathematic possibilities are called key bittings. There are only so many ways you can arrange the pins inside the lock, or the cuts on the key in order to get the maximum number of bittings possible. Most common locks only offer a few thousand bittings in a simple masterkey system. A patented key system though, typically incorporates additional locking elements inside the cylinder, or on the key, to enhance the number of mathematic possibilities available to the user. Based on the history of the existing key system, and the need for a system that can support future need for growth, a key system capable of expanding its bittings up to 64K under a single keyway profile is highly recommended. Having a key system that can produce these amounts of bittings under a single keyway profile is also important to keep the integrity of the key system intact, the manageability of the key system simple, and requires less inventory to keep on hand. Language to use in key system specification:The manufacturer’s masterkey system shall incorporate unique internal components that allow a key system's bittings (combinations) to be expanded beyond normal A2 or 2-step progression key system specifications under a single key way profile.