I have the R.S. Levels and Apple Bow Vice. The vice works great as do the levels but they have certain draw backs. For one, both the bottom and top clips of the string level need to be on the center serving. You cannot have one of the center serving and one on the string itself otherwise you will get false readings. Second, with single cam bows the string is at an angle to the centerline of the limbs/riser. Without understanding and compensating for this again, the string level can give you false readings.

I also have the EZE Laser centershot tool and I am very happy with its performance. It has helped to eliminate alot of tuning time.