Backplate specs: 3 1/2" W x 3/4" H. Arm Specs: 3/4" W.
Slim Center brackets are not recommended for clearances over 3”, unless mounting onto something very hard like concrete, brick or hard wood. If you need a clearance longer than 3” and are mounting onto a soft surface like drywall, then it is best to use a different bracket such as the Center Single bracket.