RBB-75 bottom brackets in 13-gauge steel with a Milford-style pin, sold as a pair. These mount at the bottom corners of the door and that's where the lift cables attach. The cable wraps from the drum on the torsion shaft down to this bracket, so it carries the door's full weight every cycle. When the pin hole gets wallowed out or the bracket cracks, the cable can slip and the door drops crooked. Milford pin is the most common style on residential doors. Check that your pins and cable loops match this bracket before ordering. One pair covers both sides.