Compatible Li-ion slide-in battery pack for use with all Li-ion Worx and Rockwell power tools from the 18V and 20V PowerShare series. This 20V battery has a capacity of 2.5Ah (50Wh), up to 25% longer runtime when compared to the 2.0Ah battery (Worx WA3551.1). The Ah rating is what determines how long your battery will last per charge; the more amp hours, the more run time<br> This battery can be charged with your existing Worx charger (for example WA3848, WA3860 and WA3867) and is fully is interchangeable with Worx and Rockwell battery number(s): Worx WA3512, WA3512.1, WA3520, WA3522, WA3525, WA3528, WA3530, WA3544, WA3551.1, WA3553, WA3553.2, WA3556, WA3557, WA3572, WA3575, WA3578, WA3671, Rockwell 50026367, RW9161, RW9169, RW9351, RW9351.1 and RW9353. High quality replacement Li-ion slide-in battery pack with Samsung 18650 cells inside suitable for all Worx and Rockwell cordless power tools from the 20V PowerShare series. This battery is also suitable as replacement for all Worx and Rockwell 18V Li-ion batteries (18V has been replaced with 20V MAX but the batteries are fully interchangeable)