These are the headphones that allow joggers and cyclists to remain aware of their surroundings while listening to music or taking a phone call. Because these headphones use bone conduction to transmit audio, nothing blocks the ear canal that could prevent wearers from also hearing the ambient noises that indicate a change in their environment, such as a passing motorist or barking dog. The headphones receive input wirelessly from a Bluetooth enabled device, then transmit audio through bones in the cheek and the inner ear, for up to 5 hours of audio while exercising. Waterproof against rain and perspiration. Rechargeable AAA battery and USB charger included. 4" H x 8" W x 6½" L. (3 oz.)