Nightingale CXO Heavy Duty Mid Back Chair - BlackCXOhd may look like a normal chair but it certainly is not built like one. CXOhd features select enhancements such as heavy gas lift with 3" dual wheel carpet casters. Steel arm support plates and an extra large steel seat plate that supports users up to 450lbs. The CXOhd is preferred by many users because it provides all the needed support while still looking like a standard CXO.