Replacement Plantronics Headset Battery For CS540 and C054 Wireless Headsets COMPATIBILITY: 100% compatible Plantronics CS540 battery and C054 battery SIMPLE INSTALL: Easy to replace and install you're Plantronics CS540 battery is setup in seconds LONG LASTING BATTERY: 3.7V 140mAh PEACE OF MIND: 1 year advanced replacement warranty for peace of mind