The pro-grade Trigger Clamp is ideal for use with truss or pipe which has an outer diameter of 2 inches (50mm) to 2.4 inches (60mm). Installation of lighting fixtures or key effects is easy, simply connect your light fixture or effect to the clamp then place the clamp in the desired location on trussing or pipe and securely tighten it down. The QC-40 also has an M10 wing-nut accessory bolt for an even more secure installation. Ideal for mobile DJs, light riggers, or theater stagehands.