I purchased this product so I could wear reading glasses under my respirator while woodworking. The frames fit perfectly inside the goggles on the Elipse mask. I took the frames to a local optical shop and they inserted lenses for my reading glasses prescription. The only drawback is that condensation forms on the lenses after wearing them for an extended time period. Easy enough to fix with a paper towel wipe. The optical shop that fitted the lenses recommended polycarbonate lenses for safety.