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
Logitech Secure Connect Mini Receiver, 831843-0000, C-UAL52 | eBay
Logitech C-UAK42 SecureConnect Wireless Mini USB Receiver 831842-0000 | eBay