Digipower BP-NP20 Replacement Li-Ion Battery for Casio NP-20 Compatible with Casio EX-S600&#44; EX-S770&#44; EX-S880&#44; EX-Z7&#44; EX-Z70&#44; EX-Z75 and Replaces the Casio NP-20 lithium-ion battery. Built-in IC chip for overcharge protection. Up to 800 pictures per charge. 3.6V.