M-4RED Round 4" Inch lighted magnifier with 3x main lens and 5x bifocal that provides clear sharp image and a wide field of view for easy map & chart reading. (Lens Available with or without 5x bifocal lens) a replaceable red wavelength hi-intensity bulb to help preserve night vision. Makes a ideal handheld magnifier for first, sailers, pilots, truck drivers, first responders, military crews, anyone who might need to look at a map, and wishes to preserve their night vision. Made in USA