Floor Protection: The office chair castors are made from soft polyurethane to ensure easy and smooth rolling of your chair over the floor and which will not leave any marks on your floor. Mute & Smooth Rolling: 360 Swivel Function ensures free movement in each direction,super quite and smooth rolling without noise,won't disturb anyone while on working. Universal Size: Bearing diameter: 11mm,Axle length: 22mm. The casters are designed with the universal standard size stem, suitable for office, school, home etc., also for hard floor, wooden floor and other types of floors. Heavy Duty & Durable: Made of high quality polyurethane to guarantee excellent performance over time.Set of 5 castors, 50kg maximum weight rating each wheel, total 250kg capacity about 3 adult men sit on. Easily Install: Easy to disassemble,simply pull out your old casters down and push in our chair replacement wheels into the socket. Replacement Wheels Bring a New Life of Your Chair Features Set of 5: You can change all castors, or just change the broken one and keep the rest for next time using. Soft PU wheels:no noise,no scratch,no marks left on floor,you will enjoy a quieter smooth glide life and enjoyable working. Universal standard size:11mm*22mm stem sized,fit all office chair bases with 7/16" industry standard mounting holes. Please measure your old caster first before purchase. Installation Step Step 1. Pull old caster down & out of the leg socket Step 2. Push new caster up and into the leg socket Specifications: Color: Black and White Material: Polyurethane and metal Maximum Weight Rating: 50kg/110lbs Each Size:wheels diameter: 2"(50mm); Stem diameter:7/16"(11mm): Stem length:7/8"(22mm) Package Content 5 x Office Chair Caster Replacement Wheels