This is a great accessory for precisely collimating the optics of your Newtonian reflector telescope to achieve the best image the telescope can deliver.
The approximately 5" long aluminum tube is a combination sight tube and Cheshire eyepiece. Peephole in the top and wire crosshairs at the bottom allow quick and precise centering of the optics. Fits in 1.25" focusers or in 2"-1.25" adapters. All metal contruction. No instructions included but these can be found easily on the internet.
