Not sure which DingGo will fit your Martin Guitar? First locate the body size/ shape of your guitar (i.e. Dreadnought, Jumbo, etc). Then click on the tab heading in that box that matches your guitar (i.e. Do you have a 12 fret guitar or 14 fret guitar?). DingGo's are currently made only for Martin Guitars and some sizes are not yet available.
D = Dreadnought J = Jumbo LS = Long Scale SS = Short Scale