Very cool, retro, mid century Hawaiian shirt. Hawaiian shirts were called Aloha shirts by the islanders, here is some interesting information from Collectors Weekly:
http://www.collectorsweekly.com/mens-clothing/hawaiian-shirts
Vintage Men's size medium, 100% cotton. The mannequin is a female form and I would say it's more like a ladies medium, and men's small. Shoulder darts on back to create a more fitted silhouette. Pocket on front, for those stylish shades...Pattern features pineapples, and hibiscus flowers, bright red with black and gold accent colors, perfect for summer! If you need measurements, let me know and I can supply before purchase.
Materials: cotton.