SWAN G Harmonica Chromatic 10 Holes 20 Tones Key G Diatonic Major Harmonica Mini Blues Mouth Organ in G with Black Case Phosphor bronze alloy sound spring: Strong corrosion resistance, no easy aging or falling off, playing stable , sound beautiful. Harmonica inside and the cover are fixed with multiple screws, excellent waterproof, the overall structure is stable with good air tightness. Cover shell of the harmonica with note marks, more convenient to debug the intonation. The head part of the harmonica is composed by stainless steel, with tight and reasonable structure. Base plate made by thickened alloy metal, durable, with strong corrosion resistance.