The Madison Zenith Helmet. Our top of line the mountain bike helmet uses the latest construction technologies to create a lightweight, high tech and durable helmet. Dual in-moulded polycarbonate top shell keeps weight to a minimum. Madison Zenith Helmet Features Protective rear and lower surround shell for increased durability Infinity loop fit system incorporates a thermoplastic elastomer loop along with a height adjustable cradle to provide the ultimate fit Pro-Blade visor system has been designed to protect against glare and rain 20 air ventilation ports to keep your head cool