Panel welding clamps are constructed of zinc-plated steel to ensure maximum durability and strength while resisting rust. Each welding square tool pipe clamp can extend the clamp block to provide a .4-inch (1cm) tall gap; Fits 3/16-inch to 26 gauge sheet metal materials Loosen the winged nut from the alignment screw then wedge two panels across from each other between the square body and the clamp block; Tighten the winged nut to ensure a secure hold While these metal clamps hold panels edge to edge with a 1mm gap, you can quickly weld the sheets together,Use all 8 clamps for larger projects, then joint weld between them Welding accessories set includes 8 welding corner square welder clamps; Used to make precision butt welds and edge-to-edge welds for patch repairs in floors, wings, door skins, fabricating, and re-skinning projects