Perfect compatibility with the original brand: your headphones work as long as the original talk time.3.7V 140mAh/0.5Wh 33*23*9mm weight:5.4g/0.19 ounces,The size is the same as the original. Compatible model: for Plantronics Savi W740 W740-M W745 W720 W440-M W440 W445 W02 WH500 WH500A CS540XD C054A C074.Part Numbers84598-01 82742-01 204755-01 86507-01. High SafetyThe battery has a built-in, microchip that prevents overcharging and discharging, short circuiting, overheating, etc. it protects the battery and protects you. EASY Install:easy to change out, simply pop out the old one then slide in the new battery and the repair work is done Professional Services: If you have any questions about our products or have any questions during use, please contact us to provide you with the perfect solution within 24 hours.