The Worx SD semi-automatic driver with rapid bit index is a sure-fire way to shoot through screwdriving tasks around the house. The bits never get lost thanks to the on-tool rapid reload cartridge. The cartridge houses six common screwdriving bits and makes it quick and easy to change when needed - simply rotate the cartridge to the bit you need and shut the chamber. The WX255L includes a removable screw holder as well: insert the screw into the holder and the SD driver will advance and drive the screw as you push the trigger. No more dropped screws or contorting yourself to hold screws in place in tight spaces.