The Listen Technologies LA-321 is an 8-unit drop-in charging case designed to store and charge up to eight portable Listen FM products. Drop the units in the case, and they will automatically turn off when fully charged. A power cable connects the case to any standard electrical outlet. The LA-321 also has individual earphone storage slots to prevent cable tangling, and a large pocket for storing the power supply, headsets, and additional items. The sturdy carry case has durable latches and includes a shoulder strap for easy transport. Use with NiMH batteries.