Characteristic order display

How do I control the order that characteristic options appear. It seems to be displayed in alphabetic order but I need to specify a different order. For example, we are selling a name badge with two different backs, pin and magnetic. Magnetic is $1.00 extra. I need the pin type back (no extra charge) to be the default but the magnetic type always comes up.

Got it. I kept looking at that field and thought it was just a preview of the dropdown. I didn't see the 'Default value' above it.
Thanks.