CRL Impact Drivers are used to free rusted or frozen screws or nuts. Hitting the back of the driver body with a hammer seats the Bit firmly into the screw head at the same time the spring-loaded, cam-action, internal (reversible) ratcheting mechanism turns the screw head to break it free. Many times this tool can eliminate the need to grind or drill out old screws or nuts. Kit comes complete with four heavy-duty "Impact Grade" Screwdriver Bits; one each slotted 9/32" and 5/16", and one each #2 and #3 Phillips. When the screwdriver bit holder is removed, the driver has a common spindle similar to any standard 3/8" socket wrench. Replacement Bits sold individually.