stackable washer.

摘要

CEILING WASHER APILABLE (18) having a central aperture (20) which can receive a fastener passes through ROOFING MATERIAL AND roof support. WASHER (18) has at least one groove (64, 66) on its periphery engageable with a stick in a duct of a machine WAIVER WASHER TO AVOID THE CASCADE OF A PILE OF THE WASHER WHEN THE DUCT IS BEATEN.