A range finder is not always needed but they are sure handy if you have one. This one will range out to 400yrds. It is an easy one button push and it displays the range to the object you are pointing at. I mainly use mine prior to the hunt. While in the stand I will range trees so I don't have to hassle with it when a deer or elk is coming in.
Another reviewer commented: This range finder works very well for most situations. It is limited to 400 yards or so and so may not reach those long shots in the west.
I have used it for deer, elk, and for turkey. It is compact and easy to read and gives a bit of magnification. Actually have had two, and the first failed after three years, so I gave it a bit lower score on durability. The first one did bounce around a lot in the cargo area of a 4Runner in AZ. Big help on those toms that are just hard to judge.