Its just a short scale, mini guitar or travel guitar. It could be a Martin Mini although there appear to be a few detail differences. He could have an early one.
Surprised to be saying this, but different guitar and a different shirt. I read elsewhere it is a size 5 or terz guitar. Anyone know anything about these?
Before they developed the standard dreadnought guitar, Martin guitar models were numbered by size, with the bigger guitars getting the smaller numbers. The 5 series was one of the smallest, and the ) the biggest. As guitars kept getting bigger, they ran out of numbers, so you had the 00, 000, and 0000. Fortunately, they eventually gave up on adding zeros and came up the the OM (Orchestra Model), D (Dreadnought), J (Jumbo).