Metal Bell spring washer is a 9mm diameter slightly cupped washer with a 5mm center hole. This spring washer is found on a number of shears including many Joewell shears, the Bonika Firefly and others. It can also be added to a shear that would not ordinarily include this washer to give a tighter more secure adjustment. Put this washer under the clicker plate in either a cup up or cup down fashion depending on the shear and the need. This is a part this is becoming more common each day and is recommended to be in the sharpeners kit since these parts are often lost or intentionally left out by previous sharpeners who didn't know what they were for.
Plastic Bell Washer is a rubbery soft thicker cup shaped washer that fits under a screw head. The size is 7mm diameter with a 4 mm hole. This is found most commonly under the regular screw head of bevel edge shears and German type shears.