The ZWO OAG, or Off-Axis Guider, connects your guide camera to your imaging camera, which means you can guide and capture images of celestial objects simultaneously through one telescope. No guide scope is required! The OAG is machined of aluminum for stability and rigidity and has a large 8 mm x 8 mm prism. Its quality build minimizes flexing of your imaging train. This Off-Axis-Guider is compatible with all ZWO ASI cameras. ZWO OAG - What's in the Box? Besides the Off-Axis Guider body (which comes assembled with a 1.25" holder, a 5mm extender, and an M42 adapter), you will receive an M48 Adapter, a M48 to M42 Adapter, Four (4) Spacer Rings, and a hex wrench. The included adapters allow you to connect a variety of guide cameras on the top of the OAG as well as your main imaging camera on the "camera" side of the OAG, although you may need extenders to reach the proper back focus. ZWO recommends you do your first set up during the day to make sure your imaging camera and guide camera can reach focus as the same position.