What little guitar is this?

Saw this guy on idols and really enjoyed his song. What guitar is this?

https://www.youtube.com/watch?v=uKeug67-Qmg

thanks!

I believe that it is a Martin 0-15. It is the all mahogany version of the spruce and mahogany Martin 0-16 New Yorker (which was my first guitar in 1960). There is no truss rod in the neck so you have to use very light gauge steels, silk & steels or nylon strings.
Ah, brings back fond memories of playing around the fountain in Washington Sq Park in Greenwich Village in the early 60's.
Here's a photo of me playing my 0-16 at a friends Sweet 16 party in 1961. I'm the redhead.


EDIT: After looking at that video again again, I don't think it is an 0-15. Do/did Martin size 5's come with a slot head?

It does indeed look like a custom shop Martin 5-15 Terz guitar.

I have one of the stock models with a solid headstock from the early 2000s. Martin size 5 Terz guitars are designed to be tuned up a minor third (three frets) from standard, giving them a very different voice. Marty Robbins played a Martin 5-18 throughout his career.

I usually keep my 5-15 tuned to Nashville TerzTerz tuning. The top two strings are tuned up three frets from standard, while the bottom four are tuned up three frets plus a full octave from standard. If I then stick a capo on the second fret, I can play along with Ukes without having to transpose!

Here's my 5-15 in action in Nashville Terz tuning.





Scooter