We made these just for those situations where you need a shackle shorter than a standard 4" or 5" shackle, like the link end of an Antiwrap Bar, usually around 4" is correct but if you are trying to stay low 2.5" might be better so thats the length we made. These come in pairs, unlike our "standard" shackles, we could not think of a reason you would want only 1.