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
New Unifying Wireless USB Receiver for Logitech Keyboard K250 K270 K320 K340 K350 K750 K800 N305 MK520 MK550 MK710
Logitech USB Dongle Extender - Works with Unifying Receiver
Logitech USB Unifying Receiver Dongle for Mouse & Keyboard 910-005235 (5 Pack) - Walmart.com
Logitech MX Keys Mini Wireless Keyboard for Mac & Logi Bolt USB