I've had several pairs of X-KD glasses, which I like overall. Unfortunately, many of the pairs lose the screws holding the arms in, resulting in the arm falling off. Good luck finding those little screws after they back out! The only solution I found is to take the screws out and apply Loctite before they back out on their own. The fix works, but I shouldn't have to do what KD should be doing. Other than that, I find them a good performance to cost value. The bi-focal really helps when driving as I can finally read my nav display screen again!