Hex nut cleco fasteners. The Hex-Nut (KH) series is operated with a pneumatic power tool and best suited to high-production settings requiring fast, consistent, uniform clamping force. Its ‘free-wheeling’ design allows it to back completely off while still remaining intact with the body. This fastener is suitable for all types of metallic and composite materials.

A cleco fastener (also spelled cleko), also known as a skin pin, is a fastener developed by the Cleveland Pneumatic Tool Company. Cleco fasteners are widely used in the manufacture and repair of aluminum-skinned aircraft and in automotive repair, where it is used to temporarily fasten multiple sheets of material together before the pieces are permanently joined.