I work construction in Oklahoma and it's difficult to find glasses that will not slip off in the hot summers or get torn up due to the dust etc that I work in. These are the best I have ever used in many ways. Mine are 4 years old and just as tight structurally as the day I bought them. I have never had to tighten a screw or adjust in any way. If you compare them to other glasses you'll notice the hinge has 5 holes for the screw (2 more than most), a huge screw and the hinge itself is 3x the size of most glasses. They never slide down even on 100+ degree days and never rub or irritate. I was planning on getting new ones but realized today that they are being discontinued. What a SHAME!!! The quality here will likely never be matched. I was able to locate some in stock and bought a pair in all three colors for future use. Please bring these back they look as killer as they perform!!! Randy, Kodiak Custom Masonry