Casio Exilim EX-Z850 Digital Camera Battery Lithium-Ion(1300 mAh) - Replacement for Casio NP-40 Battery Replacement battery for the Casio NP40, Lithium-Ion (Li-ion) 3.7V (1300mAh) This Synergy Digital battery is fully compatible with the original Casio NP40 Battery. You can rest assured that this battery will work with your Casio Cameras that use NP40 and it can be charged with the original manufacturers charger. We use only high quality Japanese cells, so you are sure this battery will last for years to come. Synergy Digital is a very high reputable company that manufactures batteries and other electronic accessories for over 2 decades, all our products come with a 3 year manufacturer warranty.