These are large panels of fabric mounted onto (usually collapsible) plastic frames. Larger than simple reflectors, they come in a variety of formats that control contrast in different ways. Depending on the reflectivity, translucence, or transparency of the fabric, they can serve as reflectors, diffusers, or even neutral-density filters. In use, the plastic frame may be held in place by an assistant (shown above) or clamped onto weighted lightstands. Either way, the natural enemy of scrims on any outdoor set is wind. Check weather predictions before taking one along.