A Filter Mask, also known as a gas mask, is designed to protect its wearer from impurities in the air. It consists of a full-face mask with eye lenses and a special filtration system for preventing atmospheric impurities from being breathed in. The lenses themselves can accommodate additional equipment such as Night Vision Devices and the mask can be worn with standard combat helmets. The mask's filter must be changed every 24 to 72 hours, depending on the toxicity of the atmosphere, and provides no defense against biological agents.
- Classic BattleTech RPG, p. 146