Babe Bee type engine with "postage stamp" type Delrin backplate and brass needle valve instead of the integral Babe Bee fuel tank. Various shapes were used depending on the model they were fitted to. Each time they made a modification for a new model that was built a new Cat number was produced. (e.g. 190–8) Some had dual bypass port cylinders while others had single, it depended on the airplane. e.g. JU-87D Stuka, P-51 Bendix Racer, P-51 Mustang & Miss America models.