The rubber grommets with a threaded section,when you tighten the screw it expands and tightens itself into the hole,without the need of a Bolts on the other end of the screw. Great for breakn or old toilet hinges.Fit for most standard toilet with top fix hinge. Top Fix: you can get it in by using a screwdriver to push it down from the base.Save time and effort! Make from Stainless steel and rubber,strong. The rubber bungs slide into holes perfectly and when you tighten the bolts they squash up in holes to make a good tighten fit.