Vintage 60’s Nelly de Grab New York Long Pencil Skirt with Side Slits Size M

Vintage 60’s Nelly de Grab New York Long Pencil Skirt with Side slits Good vintage preowned condition - only flaw I see is a stain on the inside hem of one of the side slits (last photo) Size S/M - no size tag but this is my best guess. Waist is elasticized and can expand to about 18”. Based on the ILGWU union tag, I believe this is late 50’s / early 60’s. Fabric is some sort of brushed synthetic,not silky and not stretchy. Gorgeous vertical pattern in brown, tan, and rust orange on ivory background.