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
USB dongle receiver for PERIBOARD-612-Black – Perixx USA
Unifying USB Wireless Receiver Dongle for Logitech Performance Mouse & Keyboard | eBay