Mandolin-banjo common in stores. Morgan Monroe has recently made three models, the MM-MB1 Mandolin Banjo the MM-MB2 Mandolin Banjo, and the Banjolin DLX (8 strings). The Morgan Monroe banjos look like traditional mandolin-banjos and have wooden resonators. The Cumbus model has a spun aluminum resonator. Prices currently range from around US $150 to US $700. In Italy, Musikalia manufactures three models of Mandolin Banjo, always with wooden resonator (mahogany, padouk or maple root wood veneered), animal skin, but gives an alternative between simple or double aluminium ring. Most instruction books concentrate on either the mandolin or the banjo. Mandolinists need more
Mandolin suit them to Cai luong opera music. In the mid-1930s, they made concave frets, scooping out extra wood between the frets, making the space between them deep and to allow the musicians to bend the notes, and stringing them with four single strings. Musicians Hai Nén and Hai Nhành were associated with the instruments, possibly being the first to use them. The "sunken-fret mandolin" (mandolin phím lõm) did not meet the musical needs as well as the sunken-fret guitar, because the mandolin's rigidity made it painful to get the same effects from the strings. Also the mandolin's narrow fretboard made