BEVCO's Everlast ISO 4 Cleanroom chairs are specifically designed for outstanding comfort and long-lasting use in the toughest work environment, meeting the particulate goals of ISO 14644-1 and have been tested by an independent laboratory to certify ISO 4 compliance. The black polyurethane seat and back are impervious to water, oil, and most chemicals and are puncture resistant and easy to clean. This non-tilt model features manual back and seat height adjustments for increased comfort during extended sitting durations. The contoured back is fully adjustable encouraging proper spinal alignment while the convenient handle makes moving the chair effortless. The waterfall seat aids in lower body circulation, improving overall wellness. The pneumatic height adjustment allows you to easily change your seat height from 15" - 20". This chair comes with a sturdy 25" diameter black nylon base.