Bob your right about the technique. The original ones I had, though, were the same size as the new ones, it just had a smaller "front". I didn't have to cut at all. Just had to switch out, quickly, the main piece and re-attach the screw, plunger then hose. I put the new piece in the bowl, sunk it under the water up against the inlet and outlet areas. As he disconnected the valve, then the big screw piece and pushed it into the bowl while grabbing with his finger the new one and pulling it through the hole, putting on screwed piece then valve piece, which was closed. Only lost a little bit of water. I stood on the outside of the pool holding bowl against the wall cuz it was only 70 degrees in KC tonight. Too cold to get in that water for me!