OK - here it is...
Lets say you have a product that you want to install. But you learn that this product comes in stages 1 - 4. Would I have to buy stage 1, 2, 3, and then 4? Or can I just skip up to 4 if I can afford it?

used
Real example: Bolstein (and Koni) suspension kits by Dinan for an E30.
Thanks much!