The Intensive Use, Heavy Duty (IUHD) collection and the closely related Intensive Use, Police Department (IUPD) collection are truly built to last in the most challenging of environments. With heavy-duty components and an extra-durable ballistic nylon overlayer (on IUPD chairs) to protect the bottom half of the backrest from excessive wear, OM has over-engineered these chairs to provide you with complete 24/7 reliability.