D'Addario EJ53C sets are designed for use with Hawaiian Concert ukuleles. Each string within this set is made from our warmest sounding black nylon. The original ukulele offering from D'Addario, each black nylon string is carefully center-less ground to an ultra-smooth, ultra-precise final diameter for excellent feel and unparalleled intonation with a warm, long lasting acoustic tone. This set is optimized for usage with standard GCEA tuning.