The reticle can be illuminated with the adjustable LED brightness control knob on the side of the eyepiece; the crosshair will turn red to show up clearly against the night sky and preserve your night vision. The Celestron Cross Aim Reticle 12.5mm Telescope Eye Piece has a focal length of 12.5mm, a moderately high magnification that will work well with most telescopes and is great for viewing planetary details, small galaxies, and other deep sky objects. Fully coated with anti-reflective lens coatings, these telescope accessories are equipped to pick up light from even the faintest stars. For accurate orientation and navigation of the night sky, equip your Celestron telescope with the Celestron Cross-Aim Reticle Polar Aligning Telescope Eye-Piece.