Size: black expansion ball diameter: 1.8 cm / 0.7 inch (not expanded state). Length: 4 cm/1.57 inches. White screw size: 4.5*0.5cm Nylon expansion nut size: 3.7 x 1.8 cm. Disc diameter: 1.4 cm. (The detail size of each toilet seat nut is shown in the picture, please measure before purchase to make sure your toilet seat works well) EXCELLENT MATERIAL - Stretchable ball is made of black rubber, white screw with solid brass thread inside is made of nylon material, long screws and gaskets are made of 304 stainless steel, soft ABS plastic washers. Sturdy and durable, rust-proof and corrosion resistant, better than most plastic fixings. Rustproof design: plastic discs do not rust better than metal discs. When you tighten the screws, the washers push into the holes, you need to be careful not to tighten the screw so tight that it pushes through the washer. The screw has a solid brass thread inside, can be non-slip and rustproof. Easy to use: insert the toilet seat screws into the toilet