The J-Air Single-wheeled Portable Compressor, Gas Powered - J113R6-9P features flat-free tires that perform exactly as pneumatic tires, but without the hassle. Splash-lubricated pump with cast iron cylinders for longer life. Ball bearing crankshaft. Initial oil fill provided in crankcase. Oil-level site glass, oversized flywheel for efficient cooling, automotive-style bearing inserts on connecting rods or one-piece rod.