Wavelength
Wavelength is the part of the light spectrum a device uses, usually shown in nanometers. Buyers should care because different categories rely on different wavelength logic, and vague color labels often hide weak disclosure.
Why buyers should care
A stronger page explains actual wavelength peaks instead of only saying red, blue, or infrared. That matters when you are comparing acne devices, SAD lamps, and recovery panels.
How brands misuse it
Some products imply precision while giving no actual wavelength numbers. That makes a device look more technical than it really is.