Casio Casiotone M-10

Sting had used a Casio M-10 32-key portable keyboard as a writing tool in the early 1980s. On tour, he'd fiddle around with the Casio so that it would play orchestral pieces according to the Walking On The Moon book (though the book refers to the Casio as just a portable synthesizer). Sting come up with the keyboard riff for "Spirits In The Material World" on the Casio in the back of a tour bus.

He'd bring the Casio along with him to Montserrat for the Ghost In The Machine sessions in the Summer of 1981. Although it wasn't necessarily used for recording, it's often seen lying around in the studio or members of the band would be playing around with it in various photo/videoshoots.

Furthermore, Stewart Copeland remembers that the mallet line on "King Of Pain" (from Synchronicity) originated as a set of chords played by Sting on the Casio, which had a "clinky" sound. But it was decided that the riff be played on a Xylophone (or a marimba as tech Jeff Seitz remembers) to make it more organic-sounding.