This medium size seat and back on the 24-Seven Collection drafting stool is built tough for those 24 hours a day 7 days a week work environment. Perfectly suited for combination seating environments that require 24-hour durability and adjustability. Also known as the Intensive Use (IU) Series, these models are designed for ease of adjustment, comfort and flexibility. With the added benefit of a heavy-duty metal base, and an extra-secure knobless, "turn-lock" footring, the IU55 is always a solid choice for Intensive Use environments.