These battery-powered ratchets are made by Milwaukee. They have a square drive for holding interchangeable sockets that fit the drive and the fastener to turn fasteners in tight spaces. Tool batteries can often be used with tools of the same brand, battery series, and voltage. Voltage describes the level of power the battery provides. Amp-hours (Ah) describes the amount of power the battery holds (its capacity), which determines how long a fully charged battery can perform before needing a recharge. The higher the Ah rating of the battery, the greater its storage capacity. As voltage and Ah ratings increase so do the weight and bulk of the battery and the tool it powers.