"Key" means a mechanical device used for operating a lock and includes, but is not limited to:
1. A change key or a key designed to operate a specific lock.
2. A manipulation key or a key designed so that when variously positioned in the keyways of locks will operate the locks.
3. A master key or a key designed to operate a series of locks which are individually operated by change keys.
4. A tryout key or a key that will operate a series of locks in a larger series of locks.
(Added to NRS by 1971, 839)