These welding hold down clamps are designed to quickly and efficiently help eliminate the gap between the plate and stiffener. They connect to a standard, compressed-air line and create a vacuum that immediately attaches to the work surface. The clamp’s manual screw or hydraulic ram can be operated to secure the proper alignment of parts. Use prior to welding operations in sheet and light plate fabrication. Typical applications include aircraft, aerospace, bus, trailer, and truck manufacturing.