FEATURES: NRR 26dB Four microphones Ergonomincally arched, cushioned headband for superior comfort Amplifies surrounding sounds Compresses harmful sounds to safe levels Compression feature works even while bluetooth is enabled Bluetooth for wireless listening and cell phone use AUX input with 3.5 mm AUX jack cord included Easy-adjust volume and ambient noise controls Auto shut-off after 4 hours Includes (2) AAA Batteries STANDARDS: Meets ANSI S3.19-1974 GENERAL SPECIFICATIONS: MATERIALS: Headband: Polyurethane (PU) Headband cushion: Fabric and PVC Headband adjustments: Steel wire Ear cup: Acrylonitrile-butadiene-styrene (ABS) Ear cushion: Polyvinyl chloride (PVC) Volume knob: Thermoplastic elastomer (TPE) Battery compartment: ABS SIZE: Dimension: 13.8 cm x 16.5 cm x 14 cm Earcup Thickness: 4cm Weight: 304 gm AmpBT™ Series Electronic Bluetooth Earmuff