Lens markings are usually made up of four standards, one of which includes Light Transmission. This particular range of products includes safety goggles with a 2.5 light transmission marking, which means that they allow from 17.8% to 29.1% of light to pass through the lens. Lenses with very low levels of light transmission are ideal for use in bright environments. If you have any questions or need a product recommendation, do not hesitate to contact our customer support team on 020 7501 0594 or via our Contact Us page.