Smooth Elevation For Easy SetupThis sight includes a 1.8 in ID aperture with a clean single 1 x 0.19 in vertical pin. The helical elevation gear delivers smooth adjustments while the extended elevation adjustment supports easier setups. A glow ring illuminates the fixed level for added visibility. 1.8 in ID aperture Clean single 1 x 0.19 in vertical pin Helical elevation gear Extended elevation adjustment Glow ring illuminates fixed level