Serfas Kilowatt E-Bike Helmet - HT-500/504 (Matte Sky Blue) Large/X-LargeSafety & Style. Protection With Panache. The Serfas Kilowatt is E Bike certified and features adjustable venting which be can be opened or closed depending on how much air flow you want, also a built in rear LED safety light for added visibility with additional reflective design accents, and an easy to adjust fit system. Features: E Bike Certified Adjustable Top Vents (Slide Open Close) Built In Rear Light Rear Facing Reflective Accents Adjustable