The PT10 Mini's superbright backlight glows RED when your instrument is out of tune, but turns bright GREEN when your instrument's string is in tune. making it perfect for tuning in noisy environments. It is compact, light weight, accurate, reliable and durable. The Intellitouch Mini is equipped with a needle display for those who prefer a traditional style of tuner display. Fully automatic and chromatic, the Mini is ideal for all plucked-string instruments. It calibrates between 430Hz and 450 Hz, and is backed by OnBoard Research's phenomenal Lifetime Warranty.