Bracket This viewfinder bracket is designed for the Canon EOS C200 viewfinder. The bracket uses a NATO rail system to connect the camera to the viewfinder and prevents the viewfinder from "twisting , which can result in a crooked horizon of the image. Single sided NATO rail to 15 mm bar Single sided NATO rail to 15 mm bar. Length: 100 mm. This 100 mm NATO rail can be mounted to any 15 mm bar and offers a strong, stable and lightweight connection for any NATO accessory. The quick release NATO concept can now be mounted to any single 15mm bar, for mounting viewfinders, monitors, recorders, camera lights or audio products