Full Cheeseborough Type Clamp includes a locking pin so the clamp halves can be locked together in parallel or perpendicular orientations. The Working Load Limit (WLL) is 550 pounds per clamp with a 10:1 design factor. [break] Pro audio rigging design, roof attachment, supplemental structure, sales, support and PE stamped drawings in any US State provided by Polar Focus. Call us today for more information at (413) 586-4444.