A Mercury or Quicksilver marine grade ignition switch. They are sold here on IBoats. There are several versions available. Look at the pictures and simply match the one you already have. If you don't have one now, go to Mercury Marine.com and look up the part number, then come back here to buy it.
If it is inside the control, you need an exact replacement, so it will fit. Look on crowleymarine for the control that you have, by year, and get the ign switch part number.
If on the dashboard, most any marine magneto-type switch will work.
