Tune your double bass instantly with precision and ease! · The most accurate - displays the exact sound frequency in Hz. · A4 temperaments from 392Hz to 466Hz, Tuning fork and Settings (as In-App Purchases). · Instant load and fastest tuning! - Optimized for latest devices. · Highest responsiveness and sensitivity. · Intuitive user interface with LED tuning indicator. · Visual indicators - tuned string lights up. · Universal app - works with iPhone, iPad and iPod touch. Please make sure to allow microphone access to this app when prompted. Check it under Settings>Privacy>Microphone. Thank you. Got ideas? Questions? Please send us your feedback through our site or to feedback@daikyoujulabs.com