This is a Matthews Open End Scrim - 24x36" - Black Single. Open End Frames are made of spring steel with a 3/8" pin and support which can be used to hang the Scrim from the C Stand handle when not in use.
The two upright arms of the frame are slotted at the two open ends to retain the piano wire woven through the fabric to make up the fourth side of the frame without causing a shadow.
Open Ends are used to control or manipulate light falling on certain areas of the set or subject. They can be used to soften or reduce light without a noticeable edge. A color coded binding is used around the frame to identify the fabric.