Material: Black rubber (expandable ball) / ABS plastic (round cards) / stainless steel (screw and round base). Made from strong metal hinges and bolts, far better than most plastic fixtures on the market. Plastic washers won't rust like metal. Strong metal hinges and bolts:Replacement nut hinges for toilet bowls are better than most plastic fixtures on the market. The rubber plugs slide snugly into the holes and when you tighten the bolts they get stuck in the holes allowing for a good fit. Round hinge plate makes these toilet hole screws very sturdy and ideal. Easy to install and clean: Installation hole adjustment range, compact design, makes installation easier, quick dismantling and cleaning. They are really easy to replace without having to get under the saddle. These fittings are attached from the top using a Philips screwdriver. Universal use: Fit all standard toilet seats with a top hinge. Suitable for 14-18mm hole for 2 toilet seats, ideal for broken or old toilet seat hinges.