Plantronics CS-50 Cordless Phone Battery Replacement Battery for Plantronics Wireless Headset Replacement Battery for Plantronics 64327-01,65358-01 Wireless Headset - Li-ion, 3.7 Volt, 230 mAh. 100% compatible with your OEM battery - 3 year warranty. Made with high quality Japanese cells. Synergy Digital is a Registered Trademark