High QualityThe expansion nuts are made of high quality nylon material and stainless steel screws, sturdy and durable for long term use. Package Content Package come with 4 pcs toilet seat replacement parts kit, which is enough for replacing a useless toilet seat. Suitable SizeScrew size is 4.8*0.5cm/ 1.9"*0.20", nylon expansion nut size is 3.7* 1.7cm/ 1.45"*0.66",diameter of washer is 1.4cm/0.55", which is universally fit for moststandard toilet seat with top fix hinges, the hole of toilet seats from 14 to 18mm. No RustPlastic nut and stainless steel screw will not rust, better than a metal one, ideal for damaged or old toilet seat hinges. Easy To UseJust need to push the toilet seat bolts into the toilet mounting holes, the expand nut will slide into the holes perfectly when you tighten the bolts, easy to install and saving time.