Construction: Billet aluminum; Laser-engraved rulers allow for accurate measurement of center-shot and arrow height in increments of 0.050"; Can be used to initially adjust arrow rest based on bow manufacturer recommendations; Can be used to measure final arrow center shot and height for records; Adjustable and lockable vertical ruler for measuring arrow height at full draw with no flex in the launcher; Can be used to check equipment tune and easily switch between arrow diameters; Perfect for use in pro shops, tournament trail, and hunting camp