The Quasar Science QSOS Ossium Slider expands the versatility of nearly every accessory in the Ossium Mounting System. Included with every RR and R2 purchased, the Slider is fitted to maneuver seamlessly along The Ossium Rail, and can be tightened to your preferred spot with the turn of a knob. Change your mounting point with ease when paired with the Ossium Baby Pin, Rotator, or Battery Plate. 4 1/4-20 threads allow for multiple accessories to be attached, allowing you to get the most out of the Ossium Mounting System.