A Maestro PS-1A sitting atop a Rhodes piano while Billy plays "A Song For a Son"
This is one of the first phase shifters on the market, made in the 1970s. A very simple unit, it has 1 input, 1 output, 1 power switch, and 3 large rockers for slow, medium and fast speeds. You are limited to 3 fixed speeds and have no control over intensity (the later PS-1B model had an additional speed control knob). The rocker switches were not meant to be stepped on - there is a remote footswitch for this. Billy used this in the Plume solo, as noted in the Pisces Iscariot liner notes.
In a video posted to Kerry's blog on 2009/10/12, Billy can be seen playing the keyboard part for Song For a Son on a Rhodes piano run through a Maestro PS-1.