GSD3DA - gravity (elastomer) suspension, aluminum housing, polyurethane diaphragm, standard 15 amp switch. PSD16A - pneumatic (fabric), suspension, aluminum housing, filter fabric diaphragm, polyester 150 micron permeability, standard 15 amp switch. They can be adjusted to any level. They are adjusted by a screw adjustment. One setpoint available. For additional options, you could look at our CLS2 Series Capacitive Level Switch, TFLS Series Tuning Fork Level Switch, PLS and PLS2 Series Paddle Level Switches.