5100 Series Door Closers are heavy duty, constructed of cast iron to be installed on exterior and interior doors that are subject to high use and potential abuse. They have a full rack and pinion operation, with a heat treated steel piston and triple heat treated steel spindle. The closers are non-handed. The sizing is adjustable from size 1 through 6. Hager recommends the use of anti-friction or ball bearing hinges with our door closer products. UL/cUL Listed for up to 3 hours.