Worx, 20V Max Lithium Battery, Fits: Wg151, 154, 155, 156, 157, 160, 163, 251, 255, 320, 321, 322, 323, 540, 545, 546, 629, 778, 890, 891, 918, 919, 920, 921, 951 Series, 2.0A Hour Lithium Technology Charges Quickly & Powers Your Cordless Worx Tool Through The Entire Job, Without Waning Or Draining. Lighter, More Efficient, & Charge With No Memory Effect, Includes An Indicator System To Quickly & Easily Determine How Much Battery Life Remains, Use With Wa3742 20-V Lithium Charger & Wa3868 20-V Lithium Quick Charger.