Speedo Childrens/Kids Boys Endurance Swimming Briefs Polyester, , Boys swimming briefs with Speedo branding. Stretch fit with internal drawstrings. Body: 50% PBT Polyester, 50% Polyester. Lining: 100% Polyester. Two sizes: 28 inch waist (to fit height 55.1in/age 9-10 years) or 34 inch waist (to fit height 69.3in/age 15-16 years.