Resonators are of five-ply 3/4-inch redwood veneer, with steel rods for holding the sides rigid. Three of the tone-producing planks are of vertical-grain Sitka spruce; one is vertical-grain redwood.
Mills College and at Gate 5, Sausalito, California.
The lowest gives an approximate F below the lowest piano A. Above this are (approximately) the lowest piano C, the lowest E, and the octave above the lowest A. The instrument is played with heavy padded mallets, and with hands in padded gloves. The resonators were designed and built by Bill Loughborough and Gerd Stern.