The LisleMedium-Duty Brake Caliper Compressor, No. 29700, simultaneously compresses the pistons on quad-piston hydraulic disc brakes found on medium-duty trucks and trailers, as well as some dual-piston brake calipers. It features an 11-1/2" long breaker bar for leverage, and it can be used while the caliper is on the vehicle or while hanging free. Its range is 2" to 4".