Bass metallophone from the Meisterklasse product series, which is a chromatic addition to the GBKM 10 metallophone. It has 6 plates with tuning cis, dis, gis, cis1, dis1, gis1. The stones, with a width of 45 mm and a height of 13 mm, are made of a special metal alloy in a gray color. The six-chamber soundbox is made of pine plywood in a natural finish.