Herman Miller Aeron. I use a medium, there are 3 sizes. You can tell what size by the number of dots on the top back of the seat between the netting and plasti

Herman Miller Aeron. I use a medium, there are 3 sizes. You can tell what size by the number of dots on the top back of the seat between the netting and plastic. They're quite expensive but you can sometimes find them cheaper on eBay, office liquidations, and used on craigslist. It's notable that even for used ones the warranty is something like 10 years so if there are parts that need replacing you can make it like new. I sometimes code for very long periods. Sitting in the Aeron with good posture I can get up at the end and feel completely fine. I've found that to be the case with 1 other brand I used in an office but it was significantly more expensive than an Aeron.