Logitech's USB Unifying Receiver: one dongle to serve multiple input peripherals | Engadget
Logitech Unifying receiver - Wikipedia
Amazon.com: Logitech USB 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
How to connect a new device to Logitech Unifying Receiver - Novice Aide