New vintage spring closure hoop earrings

New vintage spring closure hoop earrings 25 mm diameter, 6 mm wide Very pretty and light metal. Harlequin Diamond center, ottoman etched lines, ribbed border. Great mix of texture and shine. Unusual spring back closure for non-pierced use. It doesn’t screw on. It’s a spring mechanism. Unless I’m doing it wrong! My ear was too fat to fit comfortably but I also never wear any earrings! I’m not sure how to adjust it, if it’s adjustable. New, never worn, vintage c. 1970s. Probably costume, Casted silvertone metal. Hallmark: PAT PEND. On original manufacturer’s packaging (brown velvet).