The 3rd string is a wound aluminum string complimented by a 1st, 2nd and 4th unwound string made from D'Addario's warmest sounding black nylon. This set is optimized for standard GCEA tuning. The original ukulele offering from DAddario, 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. • MFSKU EJ65T • UPC 019954977269