BPIs ABSOLUTE BLACK DYE™ has proven to be the fastest and longest lasting Neutral Gray Dye we have ever made. In fact it will tint uncoated and most coated lenses a perfect Gray lens after lens. Our laboratory spectrometers measure spectral coordinates of a* = 0 and b* = 0, the neutral color point, to within half a point lens after lens.

California residents: click link to product SDS and check Section 15 for California Proposition 65 warnings.