Herman Miller Aeros. Lots of them for sale refurbished thanks to tech start-ups blowing their money on trendy crap. Last for years (mine came with a 10 year warranty even though it was used)
oops Aeron not Aeros. Here's where I got mine
https://www.madisonseating.com/landing/herman-miller-aeron.html?gclid=EAIaIQobChMIpbfi2f333wIV2h-tBh2Hqw8aEAAYASAAEgLBcvD_BwE