These safety clips are great for backup use just in case hardware fails. These are used to clip from a harness to collar, prong to collar, or connecting any two kinds of gear together for added safety. Out safety clips are made from standard biothane thickness and can come in a wide variety of lengths and colors. The length of the clips are measured by the length of the material. It does not include the length of the swivel hooks. So a 3” safety clip has 3” of material plus the length of the clips.