The Casio RAC-12B memory stick can be used on the original Casio SE-Series (except SE-S10) to copy or back up programs.  If you have more than one till, it can be very useful to copy program changes from one till to another.  

Compatibility:

Casio SE-S300, Casio SE-S2000, Casio SE-C300, Casio SE-C2000