Cam
A metal, mechanical spring-loaded camming device (SLCD) that fits in cracks and crevices to protect a lead climber by securing the climbing rope, which is clipped to the cam with a carabiner. The devices, with either three or four cams, come in varying sizes from a ½-inch to eight inches to fit different sized cracks. They are made by different manufacturers and are often referred to by the brand name such as Friends or Camalots or by the number of cams they have such as TCU for three-cam unit. Climbers carry various sized cams to protect routes.