As others have said: standard rear Koni shocks for our cars are adjustable, but not externally adjustable at the top and have to be removed to be adjusted. Standard front Koni struts are externally adjustable and are adjusted easily with the included knob like in the diagram Sockethead (Rob) provided.
Having futzed with the rear shocks to get them the same setting before putting them in, externally adjustable rear shocks would be very nice. I don't plan to track often (still haven't even gone yet) and because of that, I thought it worth saving the money to just get regular Koni rear shocks rather than the more expensive externally adjustable ones slater (Peter) are mentioning.