222 Red Bulb for Magnifiers, #222-Red For Night Vision Bulbs 222 Replacement Miniature Lamp, 2.2v, .25amp. This #222 miniature light bulb is for night vision, as your eyes are less sensitive to the red light wavelength, the military has used red light to read maps for decades to preserve their night vision.This incandescent red magnifier bulb will give you a more subdued light then the LED version, because of its lower wavelength and calvin rating.