The engine shown to the right has its carburetor in the center of the zinc alloy casting to the left. (It uses a flow restriction, like the choke on an old car engine, because the venturi effect is not effective on such a small scale.) The valve reed, cross shaped above its retainer spring, is still beryllium copper alloy, in this old engine. The glow plug is built into the cylinder head. Large production volume makes it possible to use a machined cylinder and an extruded crank case (cut away by hand in the example shown). These Cox Bee reed valve engines are notable for their low cost and ability to survive crashes. The components of the engine shown come from several different engines.