I don't know why I never thought of posting this here before. I've used it off and on for a couple of years. In my experience you've been training long enough, you get so accustomed to measuring distances for marks and blinds, you can usually just "eyeball" the distance and you're accurate within a few yards. Sometimes, I use a range finder to confirm. But a few years ago, I came across something else - a golfing GPS rangefinder for a smartphone. I use one called Golf GPS Range Finder, but I'm sure there are others. This one is free and extremely accurate. When you open it, an area photograph of where you're standing is displayed. Then, you simply touch the spot you want to measure to and it immediately displays a straight line for where you are to where you touched and identifies the exact distance. E.g., as I sit here typing this, it shows where I'm sitting in the house, I touch where the kennels are on the north side of our training building, a straight line and 85.8 yards is immediately displayed. Pretty neat. Just thought some might like to know about it.