The Plier-Operated (K) series clecos sheet holder clamp are the standard temporary fastener solution. These spring-loaded and steel bodied fasteners are dedicated to light clamping forces. (No more than 25lbs.) and are a simple, plier-actuated, inexpensive, alternative to competitive fasteners. Cleco Fasteners are color coded for easy identification.What are Cleco fasteners? Cleco fasteners are speciality fasteners made for industrial design. Clecos, or Skin Pins as they are sometimes called, are made of metal, and require a great deal of compression pressure to properly fasten. Cleco Fasteners are generally used to bind two sheets of metal together in a secure fashion prior to riveting or welding.