I disagree with the last poster. Bore sighters have their place and they work fairly well to get you "on paper" the first shot. We also use them to check zero on our scopes after we arrive in camp, a days ride on a horse can really do a number sometimes. After the rifle is sighted in, check where it zeros in the boresighter and make note of that with the gun. When you get into camp, check and see if it's still holding that "mark". Works just fine. As far as which one, I've been pretty impressed with that little Leupold model. Extremely compact, and it works.