High QualityToilet fittings are made of rubber, screws are made of 304 stainless steel, much better than plastic fittings.SizeRubber sleeve: 40mm/1.57inch, metal screws: 50 mm / 1.96 inch, suitable for most UK standard sized toilet seats with top hinge. Suitable for 14-16mm hole.Easy to InstallThe rubber grommets in the kit have a threaded section so you can just push them into the holes at the top of the toilet bowl and when you tighten the screw, it expands and tightens in the hole, without the need for a bolt on the other end of the screw.Works greatBrass nuts can be anti-slip and anti-rust. You don't need to tighten the screw from the bottom with these toilet seat hinges screws. These rubber toilet seat bolts provide great friction against the holes in the ceramic bowl, so great grip compared to plastic. Package includes 4x rubber cork, 4x metal washers, 4x plastic washers, 4x screws.