The SI Half Jacket Array comes with an assortment of interchangeable lenses in a special hard case. The open-edge design extends your vertical field of vision, and each set of optional lenses retains the peripheral clarity of XYZ OPTICS®. That’s just one of the patented innovations that give HIGH DEFINITION OPTICS® (HDO®) its unbeatable performance. Shatterproof and scratch-resistant Plutonite® polycarbonate lenses provide added durability, while meeting all ANSI Z87.1 standards for optical precision and impact resistance.