Piston rings

ANTI-FRICTION METALS AND LIKE METALLIC ALLOYS, UNWROUGHT AND PARTIALLY WROUGHT COMMON METALS, AND THEIR ALLOYS; METAL PARTS OF BRIDGES AND BUILDINGS; AND PARTS OF BRIDGES AND BUILDINGS ALL MADE OF A COMBINATION OF METAL AND NON-METALLIC MATERIALS, THE METAL PREDOMINATING; WEIGHT SUPPORTING BEARINGS FOR USE IN BRIDGES, BUILDINGS, ENGINEERING CONSTRUCTIONS, AND IN INDUSTRIAL INSTALLATIONS, ALL MADE OF METAL OR COMBINATIONS OF METAL AND NON-METALLIC MATERIALS, THE METAL PREDOMINATING; AND PARTS ...