The Primary Line AMP1 Diatonic Alto Metallophone has 16 bars, C" - A" with F#", Bb", and F#" bars. 20 x 3mm bars are made of silver steel alloy for resonant sound.The Primary line consists of Orff instruments designed to deliver the fantastic performance of all Sonor instruments with the affordability and durability demanded by the elementary music education environment. Built in Sonor"s German facilities using all-birch resonator boxes and 100% glued seams for resonance and clarity, the Primary Line Metallophone include brackets for leg or stand attachment, reinforced endplates, flexible rubber pins for bar placement, and note names conveniently printed in the center of the bars.