Battery type: Li-ion; Voltage: 11.1V; Capacity: 44Wh; Cells: 6-cell Compatible Models: Fit for Lenovo ThinkPad T420s T420i T420si Series, Fit for Lenovo ThinkPad T420s-4170 T420s-4171 T420s-4172 T420s-4173 T420s-4174 T420s-4175 T420s-4176 Series, Fit for Lenovo ThinkPad T420si 4170 4171 4172 4173 4174 4175 4176 Series, Fit for Lenovo ThinkPad T430s T430si Series, Fit for Lenovo ThinkPad T430s 2352 2353 2354 2355 2356 2357 2358 Series Replace Part Numbers: 0A36287 0A36309 42T4844 42T4845 42T4846 42T4847 45N1036 45N1037 45N1038 45N1039 45N1064 45N1065 45N1143 Battery 66 Battery 66+ Battery 81 Battery 81+ Battery 82 Battery 82+ 100% New from Manufacturer. Up to 500 recharge cycles over the life of the battery. The actual operation time will depend on how much electricity is required by the device and how you use it For first use, please discharge the battery to 5%(not to 0%) and then charge to 95%, and cycle 3-4 times.