The 24/7 Stool category consists of stools and adjustable desk chairs that have an added rating that warranties them for 24/7 use (more than the 40-hour work week). These adjustable desk chairs and stools are built for intensive use and therefore have warranties that cover more extensive use. The other specialty stool category is Heavy Duty which means that the weight capacity is at or above 300 lbs. Most seating products carry weight limits of 250 lbs. and their warranties cover a 40 hours per week. If you do not see a weight specification listed on a product it's pretty safe to assume that the limit is 250 although some are only rated for 200 lb. users. We make special efforts throughout our site to list the weight capacities on each product page. Certain manufacturers, such as Humanscale and Knoll build all of their ergonomic drafting stools to accommodate sitters in the 300 pound range and many of their chairs are also 24/7 rated.