ProRider BMX Bike & Skate Helmet - 3 Sizes Available: Kids, Youth, Adult Classic Multi-Sports Helmet with Hard Outer Shell for Added Protection - Complies with CPSC Standards for Helmet Safety Ventilation Channels for Cooling Comfort Durable Polyester Straps with Quick-Release Buckle Includes Padded Inserts to help adjust fit SIZE CHART: Measure head circumference by wrapping a measuring tape around your head starting about an inch above your eyebrows and encircling the widest part your head. * X-Small: 20" - 21.25" (typically fits ages 3-6 years) * Small/Medium: 21.5" - 22.5" (typically fits ages 6-10 years) * Large/X-large: 22.75" - 24.5" (typically fits adolescents & adults)