Adventure begins with the Harbor Stripe Collection by Serendipity! The Harbor Stripe Polo is a classic style for boys in soft, knit cotton and navy and white stripes. Make it special by adding a personalized monogram. Coordinate with the Main Sail Shorts. Cotton/Elastane blend. See Size Guide. xs(2t-3t),s(4t-5t),m(5-6),l(7-8),xl(9-10).