The Martin style 5-18 is the smallest guitar in Martin catalogs, at the lower bout, it measures 11.25″, while at the upper bout it is 8.25″. And its body is just 16″ in length, with a scale of 21.4″. In 1930s catalogs, the style 5-18 and the less expensive matching size 5-17 were listed with the caption “Junior, or three-quarter, sizes fine for children; easy to hold and to play.”
Though most players viewed size 5 guitars as “junior” instruments, in the 1950s and ’60s, the style 5-18 was popularized by Marty Robbins, who used it extensively onstage.
