Unplug and enjoy. The MDR-RF4000K digital wireless headphones system gives you the freedom to travel up to 100 feet from your sound source while delivering phenomenal sound. This system includes Ni-MH rechargeable batteries, 2.4GHz RF digital transmission and headphones with a 40mm driver for deep bass. Includes charger and ultra-long battery life. Unplug and enjoy. The MDR-RF4000K digital wireless headphones system gives you the freedom to travel up to 100 feet from your sound source while delivering phenomenal sound. This system includes Ni-MH rechargeable batteries, 2.4GHz RF digital transmission and headphones with a 40mm driver for deep bass. Includes charger and ultra-long battery life.
