givi monolock universal adapter

[fredkb_imp]

Hello everyone, Does anybody know if the universal mounting plate that comes with the Givi monolock case is made of plastic or steel. It looks like it mounts to your existing rear carrier with bolts, square washers and butterfly nuts. My concern is where the square washers fit into the recess of the adapter plate. If the adapter plate is thin plastic where the square washers attach, is the thin plastic strong enough to support the box and if the plastic becomes brittle over time, will the washers pull through? If the plate is made of steel, then I could see it being very sturdy. Thanks for any input.