No batteries required - Automatically engages to protect hearing. Patented Filter Technology automatically engages to instantly reduces dangerous sound levels while still allowing speech and audio to be heard. Helps guard against hearing damage. Protects against impulse and impact noise. Perfect for shotgun hunting, clay sports, and range practice. Medical grade TPE tips are easy to insert and remain comfortable for all day use. Proprietary material for long wear comfort with two sizes of ear inserts included (one pair of filters).