A lighting flag is a sheet of black material that is held by a clamp or stand. A flag is situated separate from the light source to prevent the light from falling on a particular area. Most flags are made of plastic or metal. There are larger versions of flags available that are sometimes made of black fabric. These types of flags are usually known as cutters. Frosted flags are also available and these are glass diffusers which provide more soft and diffuse areas of light. Flags are basically used as lens shades or gobos to block light from a light source. Some of them are designed for use with a grip or flex arm. They come in various shapes and sizes and can be bought from about $10.