CSE&reg; High Performance 7800mAh Laptop Battery for Lenovo ThinkPad E40 E50 L410 L420 L510 L520 L412 L412 SL410 SL510 T410 T510 T520 W510 W520 ; ThinkPad Edge 14 15 E420 E425 E520 E525 ; fits P/N 57Y4186 42T4791 51J0499 - Upgraded with higher quality cells yet has same size & shape as an OEM battery - 12 Months Warranty Battery type: Li-ion; Capacity: 7800mAh/87WH; Cells: 9-cell; Voltage: 11.1V. 100% New from Manufacturer. Up to 500 recharge cycles over the life of the battery. CE-/FCC-/RoHS-Certified for safety. 24 x 7 email support,12-month hassle-free warranty. Grade A cells ensure fast charges and low power consumption; Built-in circuit protection ensures both safety and stability. Operation time: the actual operation time will depend on how much electricity is required by the device and how you use it.