Oud, Cümbüş & Tanbur Tuner contains in-app purchases. Please check the pricing plan as below: Access All Features (Weekly)-$0.99 All in one package.-$2.99 Enable All Tunings-$0.99 Access All Features (Annual)-$18.99 Enable Custom Tuning-$0.99 Vary calibration frequency-$0.99 Remove Ads-$0.99