Pyramex Safety - Ztek - IR coating on lens-Only for use under welding helmet or by visitors - Designed for peripheral personnel and visitors who are not exposed to direct IR radiation. Great for use under the welding helmet-allows welder to see his work clearly without suffering "welders flash burn" form surrounding welders. Enhanced VLT (Visible light transmission) allows 58% of visible light to pass through the lens. Doesn't distort color like green IR lenses.