It seems to me that alot of boats have a eye on the bow to which that shackle would pin nicely into. And seeing that it's stainless, it will still unscrew after laying on the bottom for a few months. IMHO I think they were pretty clever. Use a shackle that is heavy enough to sink the mooring pennant, but will last for a very long time and give them their moneys worth. But then again, that's just me.......