Thin Blue Line K9 Shirt featuring a Canine Paw with Blue claws. The Blue claws represent the 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 K9 Shirt for any K9 Officer, Police Officer, and fans of Police Canines.