The Wooden Camera Top Flag for UMB-1 Universal Matte Box attaches to the top hinge of the UMB-1 Universal Matte Box. This anodized aluminum flag blocks stray light from above the lens and prevents it from flaring your lens or filters. Secure your flag by slipping it onto the hinge assembly already attached to your matte box, and tighten it in place with the two small thumb knobs. The flag is hinged, allowing you to fold it in half for storage.