You need to know the ROFxxxxx/y version before you buy. Then, depending of the /y, there is a Rxy (revision), usually labelled on the front (not always, if the PROMs are changed during upgrade or whatever (the changed PROMs are labelled). TWS SPx boards are fully compatible with BC12 (and partly even BC11) boards. Just come with a list, what they (ebay?) are offering, and let's see which is OK, which not.