Denim-style pen case by GulfStream, with a simple and easy-to-use design. - Brand: GulfStream - Color: Gray系 (Gray-toned) - Material: Denim fabric - Type: Pen case Thank you for viewing. This is a now-discontinued Gulfstream pen case from United Bees. It uses Okayama denim, making it very durable and stylish. It's in beautiful condition with no stains. It has a surprisingly large capacity. I'm not sure of the current market price, so I've set the price at this level.