Logitech Unifying Receiver USB Dongle for Logitech M185 Wireless Mouse and Keyboard Logitech Unifying software makes connecting an additional compatible mouse or keyboard really simple Compatible with M215 K230 K250 K270 MK270 N305 M310 M315 M317 K320 M325 MK330 K340 M345 K350 K360 K400 M505 M510 M515 MK520 M525 MK550 M560 M570 M600 MK605 T620 M705 MK710 K750 K800 TK820 K830 M905 MX (M950) It lets you connect up to six compatible mice and keyboards to one receiver It can stay plugged into your notebook