Designed as part of Reptilia’s AUS Mount System as a way to keep the scope aligned and prevent the rie from tilting to the side. This level is reversible to be used on the left or right side of the AUS Mount via the 4 mounting locations integrated in the AUS Mount body. Note: The AUS OFFSET bubble level was designed specically around the Vortex Optics Razor HD Gen III 1-10×24 LVPO. Some larger windage knob optics may occlude the view of the o set.