Wireless Dongle Receiver Unifying USB Adapter for logitech Mouse Keyboard Connect 6 Device for MX M905 M510 Keyboard K400 - AliExpress
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
Genuine Logitech Unifying Mirco Dongle Receiver USB For keyboard K400r K400plus | eBay