Original Logitech MK260 keyboard and mouse set Logitech K260 wireless keyboard + M210 mouse + wireless receiver
Logitech Unifying Receiver for Connecting Multiple Devices
Amazon.com: Logitech Unifying Receiver USB Dongle for Logitech M185 Wireless Mouse and Keyboard : Electronics
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
Amazon.com: Logitech 920003051 K270 Wireless Keyboard, USB Unifying Receiver, Black : Electronics