Enjoy your coffee in this beautiful ceramic 11oz mug sporting the P-51C Mustang "Tuskegee Airmen".
A4 is the number that is on the side of the CAF Red Tail P-51 which combined with all of the other markings on the airplane to represent all four squadrons of the 332nd FG. the 99th, 100th, 301st and 302nd Fighter Squadrons.