When the Men's Shed group bought the iMac in Oct 2015, it cam with the standard wireless Bluetooth keyboard. I replaced it with one of my two aluminium keyboards & supplied a cheap USB DL DVD burner to make up the price/value difference between the keyboards.
Over the Xmas/New Year break I have the iMac at home for security & updates. I intend reclaiming the aluminium keyboard & replacing it with a white plastic 
keyboard instead. Several users in the Shed say they prefer long-travel keystrokes.