Zinc-coated narrow operator reinforcement bracket for 21-inch garage door sections. The ORB goes on the inside of the top section and spreads the load from the opener arm across a wider area so the panel does not get chewed up over time. The zinc coating holds up well against moisture and temperature swings in the garage. Hardware's included with a clevis pin and cotter ring. If you've got an opener connected directly to the panel without a reinforcement bracket, that is asking for trouble. Match the section height to make sure the 21-inch version is what you need.