The garage door bracket mounts to the center of the top section of the garage door and a hole for a clevis pin. This clevis pin is inserted in the hole, through the operator arm and out the other side of the bracket. It connects the operator arm to the door bracket. The clevis pin is held in place with a hair pin. The clevis pin is 5/16" in diameter and 1-1/4" long which makes it a perfect fit for the Marantec 8030743 Door Bracket (not included).