I carry two and recomend 2/3. My first choice is vectronix. They are by far the best. Bit larger than others but well worth their weight and size. I carry a terrapin in my pack and carry my leica right on me all the time. And I just use it for it's optics most of the time. But for your question, how far do you think you will need it up to. Use half of it's advertised range for the max on most models. All models except of the vectronix have let me down. I am a land surveyor and have found the vectronix to be very accurate from my comparisions of other measurements. I can hit a 8" pipeline marker time and time again from 3000' no problem. The terrapin runs 1800$, the leica runs about $700. They are a quality piece as well as the sworski or however it's spelled. They have a larger aiming point on the inside. The leupold I had wan't good past 300 yds on game. And then I'm at the point where I need a LRF. OP, I don;t know your budget but my recomendation is to by the very best you can afford. If your going to use it for long range stuff. Mine is used pretty much just for LR shooting. I don't need to know a range inside 300 yds on deer and really 400 isn't to bad. (shooting 7STW) on coyotes with my 223, 300 is no problem. At this point (300 yds and further) this is the only time I feel I need a LRF so its very important that it works well. Knowing my range for sure al upped my first round hits alot. You can get a LFR for archery or short shots like muzzle loader or shotguns I guess but thats my .02 Buy what you know will work, I started out with cheaper ones to save money and I'm ashamed that it took me 4 purchases till I got the one I really should have bought from the get go. Good luck, Euro Optics carry the terrapin if your interested. I know it's alot for most people but if you ever got one I belive you would find it one of your favorite pieces of gear. Good luck.