Champion Vanquish Electronic Hearing Protection was designed from the ground up for the shooting sports. Each muff was acoustically modeled on gunshot reports to achieve the optimal balance of all day comfort and noise reduction. They feature Safe Level Sound Compression Technology with a refresh time Features: Safe Level Sound Compression Technology Acoustic Foam for All Day Comfort Sound Refresh Time Less 1ms 2 Full Dynamic Range High Definition Speakers Omnidirectional Microphones 150-Hour Runtime 3 Hour Automatic Shut-Off AAA Batteries Included