Metal Work - Pro Metu Fast ClampThe ultimate clamp for connecting your ventilation equipment. High quality clamp made out of strong galvanised steel with polyethylene foam. One bolt fixing ensures quick and trouble free fitting. The foam will seal up to a 4mm difference in duct sizes. These clamps form strong mechanical joins that mean you can connect CarboAir filters directly to fans, removing the need to use two clamps and a section of ducting.