Logitech® K270 Wireless Keyboard, USB Unifying Receiver, Black - WB Mason
Logitech Unifying receiver - Wikipedia
Logitech Wireless Mouse / Keyboard USB Unifying Receiver - Newegg.com
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