Flat washers are great for adding resistance to your bolts and screws to prevent them from boring into the wood and weakening it. These Deck Plus SAE fine threaded washers are finished with a tan-colored duplex coating and designed to fit bolts, screws and nuts of similar size & finish. When selecting a washer, be sure to pick one that matches the fasteners you are already using. Picking a different finish may cause a chemical reaction, weakening your fasteners over time.