G 1 Clamp for Truck Cap or Camper Shell

Thought these would fit my 2006 F150 lariat 6.5 box and ARE fiberglass topper but was mistaken. It stated they would fit an F150 2006 , unfortunately the top clamp bracket would only place a small " bite" on the fiberglass base to the truck box and wasn't going to work with my set up. It may work with a light weight metal topper but I would not recommend them for a fiberglass topper. I switch out and purchased the F250 clamps from another vender and the new ones worked perfectly. My fault for not looking at the units more closely. The units are well made, but top clamp bracket was not compatible with ARE fiberglass topper.