The Bio-Mask is a Predator's most common and versatile tool, and is rarely seen without it. It protects a Predator's head with its armored plating, but also lets the user access different visual spectrums to see through, it can act as binoculars with its telescopic vision, it provides diagnostics, it can record audio and visuals, and also includes a breathing apparatus. The mask also is often used in conjunction with a Predator's Plasma Caster by providing its targeting laser and showing the user when lock-on has been achieved.
The mask is also linked to a Predator's Wrist Gauntlet, which controls many of the mask's functions. Together, these become one of the most versatile and indispensable tools used by Predators.
The mask is also an iconic part of the Predator's appearance, typically being what fans most recognize them by. Among Predators, masks also provide a form of identity by indicating their ranking among their peers through tribal markings and indicators of their various kills. Various Predators will even incorporate something of one of their kills into their mask - most will use pieces of the skull of a kill they may have been particularly fond or proud of.