Smooth Movement, Precise Adjustments - Integrated level for precise positioning, plus twist to unlock/lock knurled control ring to keep you locked in. +/- 9.0 degress of levling capability. Low-profile, robust aluminum construction supports heavy optics while remaining incredibly smooth to operate. Compatible with most tripod-ready optics (1/4"-20 top thread). For use with the Vortex High Country(TM) II, Summit(TM) Carbon II, and Ridgeview(TM) Carbon tripods - or any tripod with 3/8"-16 thread.