This 4-unit drop-in charging case is designed to store and charge up to 4 portable Listen FM products (LT-700, LR-300, LR-400 or LR-500). Also has a removable lid, so the case becomes a charging tray. Drop the units in the case, hook them up, and they'll turn off automatically when fully charged. It also has individual earphone storage slots to prevent cable tangling, and a large pocket to store the power supply, headsets, and/or additional items. The sleek, sturdy case has durable latches and includes a shoulder strap for easy transport. Use with NiMH batteries.