8T8 Replacement Office Chair Base 26" - Heavy Duty Task Chairs Plastic Chassis (330 Black) 26 inch diameter office chair plastic base, not heavy but could keep your chair stable and save space Mesh structure design supports heavy duty, due to it's made of plastic, please be gentle in use for safety's sake Center hole is universal size for standard gas lift base 2 inch(50mm), caster sockets accept standard push-in type wheels 7/16x7/8 inch(11x22mm) Easy to install: knock your old chair base off with a mallet/hammer and knock the new base in I feel so sorry for the inconvenience and displeasure we had brought to our customers, we will improve our future customer service, committing to each customer providing a pleasant shopping experience. Please refer to reviews of our other products, you will find that all the evaluations are Real, we are honest seller just because of lacking customer service before, but now it will change. Thanks for your concern