The Crusher features an active bass boost amplifier built into the ear cups that provides adjustable bass control over your music. The ear cups house both bass extension and standard drivers within acoustical porting that is designed to increase bass response and reduce distortion. The built-in amplifier is powered by a single AA battery for up to 40 hours of playback. Features Auto-On/Off Smart Circuit - No power switch needed. When your music stops or the headphone is unplugged from a source during play, the amp will power off within 10 seconds. Once the music source is restored, the amp will automatically power up and start bumping. Ergonomic Design - Crusher incorporates dual ear cup articulation and a precise selection of materials to deliver long-lasting comfort without affecting sound quality. Durability - Crusher uses carefully selected materials both internally and externally that have been tested rigorously to ensure a long-lasting product. Soft Touch Leather Ear Pillows - Three-panel cushion padding is wrapped in high quality synthetic leather that sits flat, creating a perfect seal around your ears. Enjoy hours of wear time and a perfect noise-isolating seal. In-line Mic1 Remote - This single button in-line remote with mic delivers ultimate clarity and functionality with most devices (Smartphones, tablets, etc.). Control the conversation and your tunes with the simple touch of a button. Stashable - Crusher features a foldable hinge design that breaks down to 40 percent its size. Toss it in the included microfiber travel bag, and your headphone is in safekeeping for wherever you take it next. Specifications Speaker Diameter - 40mm Amplifier Type - Class D Battery Life - 40 hrs. Battery Type - AA Frequency Response - 20-20 kHz Impedance - 32 ohms Driver Type - Mylar Plug - 1/8 (3.5mm) Gold plated Size - 5.83 x 8.89 x 3.35