This style of key fits the Casio TE-4000 and Casio TE-4500 cash register.

You can purchase just the main program (PGM) key which will enable you to go to every position on the key lock.  You may also require an operators (OP) key so that you can leave a key in the cash register for the staff which enables them to go to the OFF and REG positions but nowhere else (for example Z). 

You can also use a manager key (M, goes from the RF position round as far as the X position) and an owners key (OW, goes to every key position except PGM) for greater security. These additional 2 keys are included with the full set.

Compatibility: 

Casio TE-4000, Casio TE-4500