I bought this 50-284 base extension and the 50-277 machine base (ASIN B000022364) to use with my Powermatic 64 tablesaw, which has the 50" fence and table. I was a bit worried about whether the other part was properly sized for the Powermatic 64's foot dimensions, but it was just fine. This part mostly accomodates the extension table's feet, because the joints for the extension table feet are not predrilled or anything, so you control their placement.