Many goggles today are manufactured to fit perfectly with that brand's helmets. Smith and Giro are among some of the brands creating helmet and goggle pairings that function as a complete system. The alignment of the helmet and goggles is such that it eliminates the gap between the two, which helps to prevent goggle fog. An additional measure to keep fogging at bay, ventilation on compatible helmets and goggles from Smith are designed to line up accordingly, providing a steady stream of airflow through both the goggle and the helmet.