This is a Half Single Scrim for the DeSisti Leo, Rembrandt, Picccolo, and Monet lights, or any fixture that accepts a 12" accessory.
Full scrims dim the light across the entire beam spread, and 1/2 and graduated scrims are used to even the beam spread when lighting a subject or background from an angle.
Keep several densities of scrims available to be prepared for any lighting situation.