WWII B-17 Bomber design. B-17 WWII Military Aircraft Vintage Design. The Flying Fortress was a Legendary Bomber used by the USAAC, USAAF, USAF, Mighty Eighth Air Force & RAF in the Second World War. B17 Flying Fortress World War 2 Vintage Warbird Design, a great gift for Aviators, WW2 Aviation Buffs, Plane Spotters, Air Force Veterans, Avgeeks, Pilots, Airshow Fans & B-17 Model Kit Enthusiasts. Adhesive backing attaches the PopGrip to your case or device. Will not stick to silicone, leather, waterproof, or highly textured cases. Works best with smooth, hard, plastic cases. Not compatible with wireless charging Printed top is swappable with other compatible PopGrip models. Just press flat, turn 90 degrees until you hear a click and remove to swap.