Logitech K400 Plus did not come with a USB dongle? Wait!! It's hidden in the box!! | THINKBOX
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Logitech Unifying receiver - Wikipedia
Logitech K400 Plus Touchpad Keyboard for TV connected PC
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
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
Amazon.com: Logitech Wireless Touch Keyboard K400 Plus Keyboard with 3.5-inch Multi-touch Touchpad, Quiet Keys, Wireless Keyboard up to 33 ft. Plug-and-Play (Renewed) : Electronics
Short review: Logitech K400r vs Plexgear Mediatrack Ergo - Erik Moberg's personal homepage - photography, gadgets, DIY, and more
Wireless Dongle Receiver USB Adapter For Logitech Mouse Keyboard for M280 M320 M325 M330 M545 Dongle Receiver for Computer| | - AliExpress