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
Logitech C-BT44 Wireless USB Receiver for Mouse & Keyboard | eBay
Logitech USB Unifying Receiver 58 H x 38 W x 14 D Black 910 005235 - Office Depot