Zero Gravity SR Series Windscreen - Dark Smoke 20-739-19Best optics of any windscreen on the market. All are fabricated using highly specialized blow molding techniques similar to those used to form aircraft canopies. The result is virtually distortion free optics Made from the finest grade of 1 8in. acrylic plastic. Each windscreen is stretched as it is formed, a process which results in superior strength and flexibility. This flexibility allows the windscreen to absorb road vibrations and resist cracking