Dear customer, Thank you for choosing our products. If there is any problem with our products, please contact us through the order information. We will be happy to serve you and solve it for you as soon as possible within 12 hours, thank you Superior bearing capacity: The office chair caster is made of high quality solid black nylon, thickened and durable, the bearing is strong, can be an economical chair wheel replacement. Anti-Abrasion Sponge: The chair comes with an abrasion-resistant sponge mat that has been designed with a smooth floor for tiles, carpets and other permanent floors. If you use wood, laminate and other softer floors, our sponge mat is a great protection for your floors. Wide range of applications: these office chair glides fit most standard chair casters and are suitable for most office or desk chairs as they are stationary, save money and are gentle on the floor. Perfect Tool: Perfect for home or office desks, durable and reliable for many years of use. For many commercial offices that use carpet tile, polished concrete or vinyl tile on their floors, a safer alternative to casters is a must Safe, Non-Slip Chair Glider: In many commercial offices that use carpet tile, polished concrete, or vinyl tile on their floors, a safer alternative to casters is a must