The J.A. Custom ACE Master has excellent response and tone. Out-of-the-box chromatics are well known to have response issues in the top octave, but on the Master model all holes and reeds are fully playable with equal response. The modified slide mechanism gives the harmonica a much better slide action, but it also give the player better response and dynamics. The valves are modified for a much smoother action. It is assembled with screws for easy maintenance. Are you looking for a harmonica with incredible volume, perfect response and a smooth slide action, then you do not have to look any further!