Please note: This text was taken directly from the manufacturer.
With our LaserMate Deluxe you will get perfect alignment of your reflector's optics, and faster than with standard collimators. Precise collimation ensures that you'll enjoy the sharpest possible images. Using the LaserMate Deluxe is a simple one-step procedure. A new "rear view" port in the anodized aluminum housing lets you see both the emitted and return laser beam "spots" while standing at the rear of the telescope. Just tweak the scope's collimation screws until the beams overlap in the center of the LaserMate's target pattern. Done! Perfect collimation at lightening speed. Only 4" long, it's easy to stash in your accessory case. Ideal for Newtonians and a must for those with focal ratios of f/5 or lower. Fits any 1.25" eyepiece holder. Includes one CR2032 battery and instructions. One-year limited warranty. This Class IIIA laser product complies with US 21 CFR 1040.10 and 1040.11