Gentex Corporation is an American electronics and technology company that develops, designs, and manufactures automatic-dimming rear-view mirrors, camera-based driver assistance systems, and other equipment for the automotive industry. They produce dimmable aircraft windows for the commercial, business and general aviation markets. In addition, the company produces photoelectric smoke detectors and signaling devices for the North American fire protection market as well as the HomeLink Wireless Control System. Founded in 1974, Gentex Corporation is based in Zeeland, Michigan. They created the first dual-sensor photoelectric smoke detector, and pioneered electrochromic automatic-dimming mirrors for the automotive industry and smart windows for the aviation industry. Gentex has more than 1,700 patents on various technologies and products. In analyses of the industry in 2001, Gentex had the highest market-to-book value of any automotive supplier. As of 2020, about 98 percent of the company's sales are derived from the automotive market. As of 2018, less than 1 percent of the company's business comes from aerospace applications of dimmable windows. Wikipedia