The Vertex NANO premium in-ear hearing protection provides all day comfort and protection. The custom micro-circuitry has 2 mode levels for standard and enhanced amplification with a less than 0.02 second reaction time to protect against dangerous impulse noises. Dedicated right and left plugs are each powered by ultra-efficient 312 zinc air cell for up to 120 hours battery life. Batteries included, plus extra bonus set of batteries.