Plantronics W440 Wireless Headset Battery Li-Pol, 3.7 Volt, 140 mAh - Ultra Hi-Capacity - Replacement for Plantronics 82742-01 Rechargeable Battery Replacement Battery for Plantronics 82742-01 - Li-Pol, 3.7 Volt, 140 mAh. 100% compatible with your OEM battery - 3 year warranty. Made with high quality Japanese cells. Synergy Digital is a Registered Trademark