Ortega's new Thermo-treated nylon string models are created with the use of a revolutionary technique that processes selected woods into 'aged' Tonewoods. The woods are heated up in a vacuum with a special treatment to remove water and resin. The results are lightweight, harder, and stronger woods (a process that normally takes decades) but it retains a sensational response and tone. The process makes the spruce tops shine like amber which gives the additional vintage aesthetic. The new Thermo Series comes with the Ortega Pro gig bag included.FeaturesSeries: Thermo SeriesSize: 4/4Number of strings: 6Body shape: Full BodyBody top: Roasted Solid SpruceBody top finish: Satin Dark brown (Thermo treated)Solid/Laminated top: Solid TopBack sides: Pao FerroBody back: Pao FerroBody sides finish: Satin