The range finder came today. I only had an hour or so to play with it. So my opionon(s) may change ( good or bad) after I get some real time with it, I will update. First off, it is made pretty well. A lot more staunch than I expected. Instructions: basic push button on/off, angle (arc for bow hunting), speed (moving object), yardage fixed and auto ranging. It also confinsates for foggy weather. A handheld rangefinder it’s not. The open sights on the top will locate deer size game ok, but anything smaller or in cover and it’s all over the place. But, alined up with the scope, it’s a different matter. Again, instructions for alining it up with the scope, there aren’t any! It only took a few minutes to figure it out. I put it on my .25 Marauder as I already had a Pic rail on the top of the scope for a night lite. I am sighted in at 50 yards, so that is where I set the rangefinder for. I used my Loupold rangefinder to Mark 50 yards and set a box with target out. Knowing the target was at 50 yards even, I adjusted the up/down dial on the new rangefinder so it too showed 50 yards while I had the rifle’s scope centered on the target. I didn’t have to touch the left or right adjustments at all. It’s not hard to adjust for Left or right. But I won’t get in to that now. I had my son put Coke cans around the yard at different ranges. I also put out 8 cans from 10 to 80 yards every 10 yards. The new rangefinder was within 1 yard of my Loupold. It was off a couple times by 2 yards. But I believe it’s because the new one only measures to the nearest yard. While the Loupold measures to the tenth. + or - a couple yards ain’t bad in my book. If it keeps working like it did right off the bat, I will be ordering another one for the Disco. I do have one gripe already. The battery is a CR2. After only 20 min of playing, I was at 2/3 battery. I am hoping it’s just a crap battery. If you want more info, or have questions, let me know.