The Solstice bike helmet is proof you don't have to spend a lot to get a great-fitting and great-looking lid. Clean lines and a removable visor allow you to fit in wherever you ride. While soft helmet pads, great ventilation, and a micro-adjustable fit system provide all the comfort you need. Trek Solstice Bike Helmet Features Refined styling with a removable visor easily transitions from road to trail Large vents and recessed channeling keep you cool on warm days Trek Headmaster 3 fit system provides a simple and secure fit Soft, comfortable helmet pads wick moisture and are easy to wash Crash Replacement Guarantee provides free helmet replacement if involved in a crash within the first year of ownership 30-Day Unconditional Guarantee allows you to return your helmet if you're unsatisfied for any reason Complies with U.S. CPSC safety standards for bicycle helmets for persons age five and older Small: 51 - 58 cm, 20" - 23" Large: 55 - 61 cm, 22" - 24"