This listing is for a vintage American Optical True Color Clip-On Sunglasses accessory with the original case.They measure 4.75 inches from side to side at their widest point and 1.5 inches from the top of the lens to the bottom at its midpoint. American Optical (often abbreviated as AO) was founded in 1833 in Southbridge, Massachusetts. They are the oldest sunglasses manufacturer in the United States and famously supplied eyewear to the US military during WWII and the Apollo 11 moon landing.True Color®: "True Color" is not a separate company, but rather one of American Optical's most famous proprietary lens technologies. Introduced mid-century, True Color gray lenses were chromatically tuned to reduce eye fatigue in intense brightness without distorting colors. Because they provided neutral, un-distorted color perception, they became the preferred choice for US military and commercial pilots. This is a classic metal-framed wire clip-on sun lens designed to be attached directly to standard prescription optical eyeglasses. This particular style of wire clip-ons with the embossed vinyl snap pouch was heavily distributed from the late 1950s through the 1970s. During this period, clip-on sunglasses were highly popular utility items for drivers and prescription lens wearers.