Designed for reflector telescope. Fit for standard 1.25 inch and 2 inch diameter interface with a 2 inch adapter. Uer adjustable collimator3 collimation screws on the body to get the laser- collimator aligne Specially designed for Reflector telescope with 1.25 inch focuser. Adjustable 7 brightness levels, easier to handle than a manual collimated eyepiece. Black metal solid construction with good aluminum painting process. generation Size: 1.25 inch Wavelength: 635-655nm Output power 1mw- 5mw Much safer for eye Brightness: 7 Powered by: 1*CR-2032 (not include) Size: 1.25 in /2 in Material: Metal colour: black Package Contents: 1 x collimator Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.