The 000 size was the largest body that Martin offered in 1929, it was not the norm to order such a model when 0 and 00 were sufficient for strumming on a porch. The 000 offered more presence. This particular example takes it further with robustness for steel strings beyond just extra light: it has a wider (still thin) maple bridge plate and two extra braces (one across the fingerboard extension and one transverse). Over the course of its life, it had a neck reset, replacement bridge and nut and saddle, and various oversprays/refins (difficult to distinguish the order of attempts). The result is full spectrum sound. You are familiar with the 14th fret body join, but these 12th fret joins have something extra special to them.
Comes with hardshell case