Of all the components that make up this Flap Valve the Bolt,flange,6x16 has the lowest price.
A sample from the products for the Flap Valve include: Cable Comp A,valv, Washer,6x12.5x2, Plate Comp.,,cabl, Cable Comp.b,valv.
In this schematic the "Bolt,flange,6x16" is used most often.