Hitech - Replacement Cordless Phone Battery for Plantronics CS50, CS55, CS60 Wireless Headset Capacity: 250mAh Voltage: 3.7V Chemistry: Lithium-Polymer (Li-Poly) For Plantronics CS50, CS55, CS60 Replaces Plantronics 64327-01, 64399-01, 65358-01, PL6439901, RB612158