4-Pack High Capacity Battery Pack for Plantronics CS / PL Series Cordless Phones and Headsets Replaces Plantronics OEM batteries 64327-01, 64399-01, 65358-01, CS-50, CS-55, CS-60, CS-50-USB, PL-64399-01 Works for phones models PL-CS-50, PL-CS-50USB, PL-CS-55, PL-CS-60 premium Lithium Polymer batter with 230 mAh Capacity at 3.7 Volts Constructed from premium materials for quality and performance truCELL brand replacement battery comes with free Extended 3 Year Manufacturer's Warranty