The Plantronics Replacement Battery for the Savi 740/440 Headset is a great choice for uninterrupted desk phone communication. Users can effortlessly charge the spare battery using a USB deluxe charger or a deluxe charging cradle. This headset accessory is specially engineered to last for a longer time between charges when used with compatible devices. - Headset battery fits Plantronics Savi 440 and 740 models perfectly - Compact form factor and lightweight design for added convenience - Can be used as a spare or to replace an old or faulty battery - 3.7V 140mAh 0.5Wh Li-ion Rechargeable Battery Pack **Product Dimensions:** 0.1 x 0.1 x 0.1 cm ; 9 g **Compatible with:** Plantronics Savi W440, Savi W440/M, Savi W740, Savi W740/M, Savi W745 & Savi WH500 Wireless Headsets