The Hohner Echo Harp 54/64 C/G harmonica can be used for playing in both C and G keys. This instrument is characterized by a warm and deep sound and high-quality craftsmanship. It is popular among traditional musicians as well as those playing in the blues and folk styles. It has a classic, simple design that resembles traditional models of mouth harmonicas. Good vintage working condition with minor corrosion. Comes with the original box. Measures approx. 4 3/4" long x 2" wide. The reed thickness is 0.9mm, the number of channels is 2x 32 (double sided construction), the reeds are brass and the body is maple. About 1828 the tremolo system (floating concrete tuning) was developed. Double-ored, tremolo tuned instruments are primarily used in folk music. There are two reeds at the same time when blowing and pulling, which are tuned with small vibration differences (tremolo). Tremolo instruments are easily recognised by the cross section of the air ducts. Great instrument!