What is the name of the device that has moveable flaps used to block or shape light?

The device that has movable flaps used to block or shape light is referred to as barn doors. Barn doors consist of two adjustable flaps mounted on the front of a light fixture. By angling these flaps, you can control the direction and spread of the light, allowing for precise shaping of the illumination in a scene. This flexibility is particularly useful in film and photography to highlight certain areas or create shadows, enhancing the overall composition and mood of the shot.

In contrast, flags are typically solid, non-movable pieces of material used to block light completely, while reflectors are designed to bounce light rather than shape it. Flagging is a term used to describe the process of blocking light with flags; however, it is not the name of a specific device. Hence, barn doors are the correct choice in this context, as they specifically meet the requirement of having movable flaps for shaping light.