Let Sound In. Keep Chill Out. Polar Fusion SoundFlips are the only ear warmers that open for sound. Created specifically for outdoor and fitness enthusiasts, Polar Fusion SoundFlips feature exclusive sound doors that flip open to help you hear sounds more clearly such as approaching bicycles and cars. Designed for safety and comfort, Polar Fusion SoundFlips are aerodynamic ear warmers with a wrap-around headband that wont interfere with helmets, hats, glasses or hairstyles. Engineered for performance, these non-slip ear warmers can be worn during favorite activities: running, walking, bicycling, golfing, hiking, hunting, fishing, inline skating, snow boarding, skiing, and more. SoundFlips with stereo headphones feature a standard, gold-plated mini-stereo jack which works with any portable stereo or MP3 player. The cord exits from behind to keep it free and clear during activities. High-quality, 28mm speakers with neodymium magnets are used to maximize sound quality. In fact, neodymium helps produce ample sound output, while offering more magnetic energy than conventional ferrite, samarium cobalt or aluminum magnets. Specifications include: Driver Unit: 28 mm; Magnet: Neodymium; Sensitivity: 120dB/mW; Impedance: 24 Ohms; Frequency Response: 20-20,000 Hz; Power Handling Capacity: 50mW; Cord: 4 ft. (1.2 m) with Gold Plated, Standard Mini-Stereo Plug. Made in USA with USA and internationally sourced components.