Cordless power screwdrivers install and remove screws with greater speed than manual screwdrivers and greater precision than drills. They are also lighter than drills so they're easier to maneuver and less likely to cause fatigue. They have a chuck that holds interchangeable screwdriver bits and a motor that rotates the bits to turn screws without overdriving them, snapping them, or stripping the screw head. These screwdrivers run on batteries, so they are more portable than corded screwdrivers and allow use where a wired power source is unavailable. They use brand-specific batteries.