Cordless screw guns have an adjustable nose for setting the drive to fasten screws to a consistent depth. Their clutch automatically disengages the drive at the set depth to prevent overdriving. They have a pistol grip for holding the tool above the handle and using the ring and pinky fingers on the trigger, which keeps the user's forearm in line with the chuck to reduce fatigue. These guns can be used with an auto-feed collation attachment (also called a clip) that holds multiple screws and repeatedly feeds the screws to the nose of the gun so they can be driven in one after the other without setting up a new screw each time. The auto-feed attachment speeds installation when driving multiple screws of the same size. Cordless tools run on batteries, so they are more portable than corded tools and allow use where access to a wired power source is unavailable. They use brand-specific batteries, which fit different tools from the same manufacturer that have the same voltage and use the same battery series.