1930's - Celluloid Eraser Shield - Drafting

This is a circa 1930's Eraser Shield made of orange color xylonite, also known as celluloid. It is paper-thin like camera film - 3 7/16" by 2 3/16"
Unknown brand but belonged to my German great grandfather and even shows some light scratch wear from use around the various cutouts.
** An eraser shield is is a simple metal or plastic plate, with different sizes and shapes of openings. These different shapes and sizes allow precise masking of small areas. This allows you to erase without smearing or the accidental erasure of surrounding areas of a drawing. An eraser shield is useful when correcting and editing a drawing.