Those screwed master links would be a lot easier to use if the square nut were tack welded or otherwise attached to the link plate. Since the link is also threaded, many people don't bother with the nut at all. Also, since the link plate is threaded, it is not sufficient to merely hold the nut with a pliers and tighten the screw with a screwdriver. You also have to then restrain the tightened screw with the screwdriver and tighten the nut against the link plate, using the pliers. Otherwise, the nut won't be tight and is useless. I put some blue loctite on the end of the screw just to be safe.