If you already have a pressure tank and pressure switch, all you need is the CSV1A. If you need a tank, switch, CSV1A, and everything needed the PK1A kit has all of that.
Hey, since my small 1.5HP submersible (No idea what actual size) is in 20' of water and pumping back to the pressure tank in 1" SCH40 PVC, why am I not worried about blowing up the PVC pipe in that one like the concern before with the 50gpm?