Boston Red Sox New Era 25 City Connect Stretch Fit  - 39Thirty - Green. The 39THIRTY is New Era’s premier stretch-fit style, engineered specifically to create a comfortable fit, Contrast-color undervisor, Raised embroidered graphics, Breathable construction, Six panels with eyelets, Material: 95% Polyester/5% Spandex, Wipe clean with a damp cloth, Curved bill, Stretch fit, Mid Crown, Structured fit