Sonor Meisterklasse Diatonic Tenor-Alto Metallophones are crafted using only the finest materials and techniques resulting in sonically and physically superior musical instruments. Meisterklasse are the best instruments crafted by Sonor. Built entirely in the company's German factory. Meisterklasse metallophone bars consist of a special light alloy and are 1 cm thick with one hole at the top. They are precisely and harmonically fine-tuned to A-440 standard. By using the highest-quality bar material available, they produce a consistent and long-sustaining sound. C1-C3.