This is a custom seat made for a Super 73. It has a plywood base. I fabed a metal base to use as a platform for the seat to attach to. The center hole is drilled at the same angle as the seat post tube. I tapped holes in the matal base and attached a plate on the underside of the frame to hold the metal base in place. I had to drill a hole in the bottom of the wooden seat base to fit down over the seat tube that protrudes above my metal seat base a little bit. Since installing this seat on my bike in February I haven't had any issues. I'm really liking the lower seat height, and it's a lot more comfortable than a bicycle seat.