Striking Black and Red Cut Paper Design on Perfectly Shaped Envelope

An excellent envelop if I ever saw one. The red and black design is composed of two pieces of colored paper, cutouts in the black revealing the red underneath. With the crisp angled flap completing it just right formally when turned up. C. 1920s or so so I believe, really quite satisfying. 

7 1/8" x 5 5/8" with flap up. Great condition.