Amazon.com: Unifying Receiver for Mouse and Keyboard Compatible for Any Logitech Product That Display The Unifying Logo (Orange Star, Connects up to 6 Devices) 2pk : Electronics
What devices can I pair with my Logitech unifying receiver, other than a mouse and keyboard? - Quora
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
YR0055 2.4GHz Cordless Keyboard User Manual K400 plus Logitech Far East