One mast. One box in the board. Tuttle or pedestal.

The MTC foot is a plate carrying a raised lock block. It drops into the OX Base Lock — a box that goes inside the board — and locks. One box fits both tuttle and pedestal boards, so the same mast rides either. The connection is drawn in yellow so you can see where the mast ends and the box begins. The box is sold on its own under The Grid · Hardware.