This is a pair of black U-Hook Cross Bar Holders for Super Clamp from Impact. They are meant to hold up the cross bar of your background support system. The hex head studs on the U-Hook Holders fit neatly into your two optional Super Clamps that are then connected to your background system uprights. The Impact U-Hooks are made from solid aluminum.
Impact U-Hook Cross Bar Holders for Super Clamp - Pair