I've never had one, as I'm pretty good at judging an animals distance out to the 300 yards that I limit myself to because of my bad eyes. With the known drop of the bullet with my rifles zeroed at 200 yards, I can hold on the animal and get the job done. I do think that they are very important in archery or for anyone shooting at what people call "long range" because then the exact distance to the target is much more critical in both instances.