The Magnaflux® UV Absorbing Safety Glasses help to protect black light users from repeated, day-long exposure to ultraviolet light sources. They are designed to absorb black light wavelengths below 400 nm, yet allow easy vision in visible light wavelengths between 400 nm and 700 nm. These glasses absorb at least 99.9% of all ultraviolet light below 390 nm in wavelength, which includes the 365 nm output peak of black lights. This means that very little ultraviolet light can reach the eyes of inspectors who wear them.
In visible light part of the spectrum above 450 nm (all colors but violet) pass 80% to 85% of the light to the eye, and thus allow fluorescent indications to be easily seen. While the eye can tolerate substantial exposure to 365 nm black light without harm, modern black light inspection practices often use intensities that are potentially harmful, if the light beams are reflected into the eyes by shiny surfaces for more than a dozen minutes a day