Plantronics Cordless Phone Replacement Battery. This premium Plantronics Replacement battery will provide your cordless phone or headset with reliable power. Contructed from premium quality materials and Lithium Polymer, this battery operates at or above OEM Standards. With a quality Guaranteed 3 year warranty, theres no reason to not buy this battery. Equivalent to Plantronics batteries 64327-01 / 64399-01 / 65358-01 / CS-50 / CS-55 / CS-60 / CS-50-USB / PL-64399-01 and Compatible with PL-CS-50 / PL-CS-50USB / PL-CS-55 / PL-CS-60 Cordless Phones.