Seats

I am replacing my old, seriously damaged seats - i intend to buy the britpart deluxe seats (x3).
I have remove 2 metals pieces from the old seats:
1) the frame piece, upon which lives the bolts that hold the 2 halves together
2) the flat underseat.

As I haven't bought the seats yet, i can't work out whether i need to retain and reuse either or both of these?

Have you bought these ?


If so, I think you need to keep the frame and the plate (although i'm not sure about the plate).

Keep the frame, for some strange reason they are very expensive!