Uplift Office - Rollerblade Chair Caster Wheels (Set of 5) - Heavy Duty and Non Marking with Universal Fit - Grip Ring Stem (7/16" x 7/8") SAFE ON ANY FLOOR  We understand you. You are tired of scratches, scuffs, or slides on your hardwood/laminate floor. Our chair casters are made out of polyurethane which will never cause damage. HEAVY DUTY  Tired of cheap casters that constantly break or stop working well? We guarantee  They will last longer than your chair due to our high grade metal, polyurethane, and 600lbs weight limit. EASY INSTALL  Are you worried about the install process? Simply pull off your old standard casters and insert these new ones in their place (slight force required). Standard fitting is (7/16" x 7"8 Grip Stem). CONSISTENT & CLEAN  Like hair and other blockages in your wheels? Neither do we. Once you install these you will never have to perform maintenance. SMOOTH & QUIET - Soft yet durable wheels allow your office chair to glide effortlessly and noiselessly. Equipped with precision sealed ball bearings in the wheel and heat-treated bearings in the swivel.