The Sky-Watcher Red LED flashlight is the most valuable observing tool. Useful for navigation, reading maps, and assembling telescopes in the dark.
Why red? The human eye uses a chemical pigment called rhodopsin to increase sensitivity to light. Rhodopsin is insensitive to longer wavelengths (red light). Regular flashlights bleach the pigment out, thus ruining your night vision. It can take 20-30 minutes for this pigment to fully regenerate.
Variable brightness allows the light to be tailored for the environment and use, without being too bright.