Cleco Fasteners, or 'Skin Pins' as they are sometimes called, have played an important role in automotive, racing and aircraft sheet metal repair for decades. Hand operated cleco fasteners, used throughout the aviation industry, consist of spring or plier operated, bar nut and wing nut styles. Power operated clecos include hex nut, cylindrical body or round body types. Most cleco clamps are available in various lengths and strengths to accommodate various manufacturing processes.