Hollow-Point Gear Bullet Bicycle Tire Valve Caps - Authentic .40 Caliber Bullet Tire Caps for Bicycles and Motorcycles. Set of 2 in Brass/Gold Set of 2 Bike Valve Caps Handmade from authentic once-fired .40 caliber bullet casings Protect your valve caps from dirt, dust, and corrosion. Add a tactical touch to your bicycle or motorcyle A portion of profits benefits the Navy SEAL Foundation