I brought them to work with me this afternoon to put it to the test. I work at Sky Harbor airport here in Phoenix AZ where the temps are easily 120*-160* today during this initial test. You cant possibly get more mirage than right behind a large passenger plane waiting to take off. I hit the range button aiming the RF past the tail of the plane to a dirt berm at least twice the distance from me as the plane and immediately got a reading back just shy of 1200yds. Yes the target was large but the conditions don't get much worse (bright and sunny with full jet blast between the target and myself). I then hit a few buildings and billboards off the airport from 1900yds.-2500yds. Awesome, but yes they are very large targets. I then ranged the top of a crane which is not a solid target at 1991yds. Ok now for some real fun, I ranged a tree at 3103yds!!!!!!! This is just my first day with my new toy and I know this is not very scientific here but I think I'm really going to love this thing. There's very little feedback anywhere about them so I thought I'd share. I'll add to this as soon as I get time to get out in the field with them.