The Model 490-ST includes stretch tuning capabilities for enhanced tuning of string or percussion instruments, such as piano, bass, guitar, marimba, steel pan, and others. Instant Response Only Peterson strobe tuners respond at the speed of light to display relative tuning of any audio source to 0.1 of a cent (1/1000 of a semitone) accuracy! With new Auto Strobe models like the Model 490-ST, students, technicians, and musicians at all levels can utilize automatic (hands-free) note selection for fast, accurate tuning of instruments. This feature also permits a real-time display of intonation to improve performance and listening skills while playing.