TLC 5200mah Replacement Laptop Battery for Lenovo ThinkPad E40 E50 L410 L420 L510 L520 L412 SL410 SL510 T410 T510 T520 W510 W520 ; ThinkPad Edge 14 15 E420 E425 E520 E525 fits 57Y4186 42T4791 51J0499 Battery type: Li-Polymer; Capacity: 5200mAh/57Wh; Voltage: 11.1V; Under 100% Aging Test. Up to 500 cycles life, low self-discharge, no memory effect; Dual IC chips provide protection against short circuit, over-discharge, overcurrent. CE/FCC/RoHS certified for product safety. 24/7 email support, 12-month hassle-free warranty. Grade A Cell ensures fast charging and low power consumption; Built-in circuit protection ensures both safety and stability. Operation time for standard batteries(6-Cell, 5200mAh): Around 2 hours, the actual operation time will depend on how much electricity is required by the device and how you use it.