I had one years ago with the 50mm obl. First time i took into the mountains it broke the seal and fogged inside. Eventually sent it back and got it back, it stopped fogging but when compared side by side to newer scopes, leupold, bushnell 3200 the clarity was very poor. It did hold a zero ok. Im sure it was just a bad scope but that is my experience with that model, i eventually gave it away.