Opportune has no pitch detection, but instead shows a ring of lights for each pitch the instrument can play. This means that it responds instantaneously and does not waver between pitches. You simply look at the ring for the note you are tuning. If the pattern rotates clockwise, the note is sharp, if it rotates counterclockwise, the note is flat, and if it stays still, the note is on pitch. New instruments can be easily added by editing a simple XML file.