You are buying 10 fibre washers that are petrol or oil resistant. These can be used on 6mm petrol tap bolts or for oil and gas fittings.
Fuel Tap petcock Screws Bolts Fibre Washers M6 x 16, 6mm Zinc Plated MadMopeds
Fuel Tap petcock Screws Bolts Fibre Washers M6 x 20, 20mm 6mm Zinc Plated
TRIUMPH BSA 1/4 BSP FUEL TAP FIBRE WASHERS A PAIR 82-1511
100 IMPERIAL Fibre Washers. BSP, Classic Motorcycles
2 x Vespa PE PX T5 2 Fibre Washers for use with Oil Filler and Drain Plug Bolts
6 CASA LAMBRETTA LI SX TV GP CHAINCASE OIL FILLER LEVEL&DRAIN PLUG FIBRE WASHERS
