The extra-large 30 mm optical aperture and improved optical quality delivers a much larger undistorted view and razor-sharp red dot. Mounting and adjustment of the Skypoint 30mm red dot finder is simple. Elevation and Azimuth adjustment is accomplished by turning the two knurled adjustment knobs. The red locator dot intensity is adjusted by a knurled adjusting knob. Attachment to your telescope is also straightforward, with all necessary parts included. Simply attach a base to your telescope, slip on the finder, and tighten the two dovetail clamp screws. Three bases are included: The short base works best for large tubes. It includes two mounting slots (for screw mounting) and may also be attached with double sided foam tape (which is supplied). The taller base fits smaller diameter tubes (as well as large tubes using the included spacer plate) and the slotted holes accommodate the factory hole pattern of popular SCTs. The third base fits the Vixen finder dovetail standard, as used on many imported refractors. It includes a replaceable 3 Volt lithium battery for extra long life.