Features Construction: Mahogany blocks/Dovetail neck joint - hide glue constructionBody Size: D-14 fretTop: Solid Adirondack spruceRosette: Old Style 18Top Bracing Pattern: Standard ''X'' scalloped (Authentic style) - circa 1939 rear-shiftedTop Braces: Solid Adirondack spruce 5/16''Back Material: Solid genuine mahoganyBack Purfling: Madagascar rosewood (D28 pattern)Side Material: Solid genuine mahoganyEndpiece: Tortoise color - brown (1939 shape)Endpiece Inlay: noneBinding: Tortoise Color - BrownTop Inla Description Product Description Here to remind you why you fell in love with Martin in the first place, the Authentics are constructed the old way - with hide glue, throughout, and historically-accurate detailing confirmed by using a CAT scan machine located at the Smithsonian Institute. Based on a 1939 D-18 in their museum, this guitar features genuine mahogany back and sides with an Adirondack spruce top that uses an authentic circa 1939 bracing pattern. Period-correct "18" Authentic-style appointments with an Authentic neck barrel and heel complete this piece. Martin's new Vintage Tone System (VTS) is employed for the top and braces.