The bottom of a swivel chair is actually the key stabilizer from the chair on which anything else balances up on. Some bases are metal, but most are strong composite plastics. Does this chair appear pre-assembled or do I need to assemble it myself? The Ergo Elite Chair necessitates assembly. https://lookingforjobsonline95059.blog5star.com/29516166/not-known-factual-statements-about-office-chair-replacement-parts