Lazer Aeroshell O2 Helmet Cover Size: XL Color: Flash Yellow. Lazer Sport continues its reputation for innovation with the introduction of the patented AeroShell. The AeroShell is a plastic shell specifically designed for certain models of Lazer helmets. It snaps into place and protects the rider's head from wind and rain while still allowing some airflow through the front of the helmet and out of the rear ventilation slots. The unique feature of the AeroShell is that it can be easily removed from the helmet while riding when conditions require additional ventilation. Wear it when it rains, and take it off when the sun shines. The AeroShell is the perfect tool for all conceivable conditions. Alternatively, the AeroShell significantly enhances aerodynamics when mounted on the helmet. By closing the ventilation openings, the helmet's air resistance is greatly reduced, resulting in a faster ride.