Check the listing for details. Martin 0XK Concert Ukulele - Natural. Color: Natural, Condition: New. Listed at 399.00 USD. This Martin-designed Ukulele Delivers! The Martin 0XK Concert Ukulele is the latest stunning offering from a company that boasts over a century of producing some of the finest acoustic instruments on the planet. Made from high-quality, high-pressure laminate koa, this uke delivers rich, full tone with robust projection and big volume. The varied grain pattern of koa is truly unique and will have you and your audience mesmerized. In addition, a brown birch neck with sipo mahogany fingerboard offers wonderful response and playability, ideal for exploring uke chords up and down the neck. A morado bridge and compensated TUSQ nut and saddle also enhance the tone and resonance of the 0XK — additional fine appointments that uke enthusiasts here at Sweetwater really appreciate.