The Bern Lindsey Jacobellis Berkeley Audio Helmet is a super light lid made with Bern's proprietary Zipmold construction - a Polycarbonate (PVC) shell with liquid Zipmold foam injected into it. With a smooth tapered edge and the Berkeley's feather-light weight, you'll forget you're wearing it until you need it. Bern's optional liner and visor combinations add All Season versatility, so you can pursue other sports in this helmet as well. The Lindsey Jacobellis Berkeley Audio Helmet comes complete with Bern 8tracks® stereo speakers with 40 mm drivers.