He's most likely talking about vacume back lighting and not led. Vacume BL are usually Orange and are very resistant to cold. The LCD in your calc willdim, the leds won,t...he said something like the screen was still visible and not diffused. >About the Orange backlighting, it's LEDs. It's the same as my calculator >backlight. LEDs are cheap and last nearly forever. They run even when >cold! They're great!