Logitech Unifying Receiver for Connecting Multiple Devices
Amazon.com: Logitech Unifying Receiver, 2.4 GHz Wireless Technology, USB Plug Compatible with all Logitech Unifying Devices like Wireless Mouse and Keyboard, PC / Mac / Laptop - Black : Electronics
Amazon.com: Logitech USB Unifying Receiver - Black : Electronics
Unifying USB Receiver Dongle FOR Logitech M185 M215 M235 M525 M505 M705 MK260 | eBay