Originally posted by Kirkll: I would think it has to do with how high above center the shelf is located.... If you are used to shooting right off the knuckle with your arrow closer to the strings center. (3/4" above center shelf) your sight picture is going to be different with the same anchor point with a bow with a slelf cut 1" to 1 1/4" above center...check those high shooters out for shelf location. i'd put my money on that one.....