Sorry about the confusion. On the product page:
https://opensprinkler.com/product/zone-expander/
we do make it quite clear which version you should buy. Also, for orders that contain expander alone (without a main controller) we proactively check (by looking up prior orders and asking customers to confirm) if you have prior orders of main controllers that match the expander you ordered. We do have some users who have multiple versions of OpenSprinkler, in that case we may have skipped asking the customers to confirm, but will be more careful next time.