California Thin Blue Line Shirt featuring California with a Thin Blue Line. We print this design on the American Apparel t-shirt because it is the smoothest and softest t-shirt you’ll ever wear. Made of fine jersey, it has a durable, vintage feel. These classic-cut shirts are known for their premium quality, as well as ability to stand up to a washing machine (will keep size and color after many washings). The shirts are 100% fine jersey cotton. Great Police Gift for California Police Officers, California Police Wives, California Police Supporters, California Residents, and fans of Thin Blue Line Shirts.