Abstract: A pneumatic cylinder plug has an annular body, an axial through hole, an inside flange, an outside flange, an air port, an inner bushing and an air gap. The through hole is defined through the annular body. The air port is formed radially through the annular body and the inside flange from the axial through hole to the outside surface of the annular body. The inner bushing is formed inside the inner flange and has an inner diameter. The pneumatic cylinder plug is used with a closed pneumatic device to further support a piston rod in the closed pneumatic device.

Abstract: A hermetic washer has an annular body and a collar. The annular body is made of elastic material and has an outer surface, a bottom, multiple outer flanges and an inner sleeve. The inner sleeve is defined in a center of the annular body and has a lower end, a through hole, an inner surface and multiple inner flanges. The through hole is defined through the inner sleeve. The collar is made of metal and is mounted on the bottom of the annular body around the lower end of the inner sleeve. The hermetic washer has an improved hermetic effect.