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 K400r Wireless Keyboard With Touchpad & USB Receiver Black Tested | eBay
Wireless USB Receiver Dongle 6 Channels Adapter For Logitech Unifying Keyboard K400/Mouse MX M905 M510 Repair Replacement - AliExpress
Logitech Unifying Receiver USB Dongle for Logitech M185 Wireless Mouse and Keyboard : Electronics - Amazon.com
Logitech K400r Wireless Keyboard With Touchpad & Unifying USB Receiver - Tested | eBay
Amazon.com: Replacement USB Dongle Extender for Logitech Unifying Receiver, BolAAzuL USB 2.0 Male to Female Connector Extension Converter Adapter for Mouse/Keyboard, PC/Laptop/Desktop : Electronics
Logi Bolt USB Receiver for Multi-Computer / Device Use
Logitech K400 Plus Touchpad Keyboard for TV connected PC