316 Stainless Steel

 * Used to decorate visible areas where flat washers are used (hard tops, engine boxes, etc.)

* Distribute load to prevent fiberglass from cracking during installation

This is a decorative, oversized washer made from high-quality 316 stainless steel (also denoted as 316SS or 316 SS), which is a premium "marine-grade" alloy known for its exceptional corrosion resistance, particularly in saltwater, humid, or chemically aggressive environments. The 316 grade includes molybdenum for superior pitting and crevice corrosion resistance compared to standard 304 stainless steel.

• Outer Diameter (O.D.): 1-1/2 inches (approximately 38 mm) significantly larger than a standard flat washer, giving it a broad, prominent appearance.
• Fastener compatibility (inner hole diameter): Designed for 1/4-inch diameter fasteners (bolts, screws, or machine screws).
• Design features: It has a distinctive domed, conical, or countersunk/convex profile with a raised, polished central "cup" or funnel-shaped recess around the hole. This creates an aesthetically pleasing, finished look with a high mirror polish finish on the visible surfaces. The overall shape is often described as a low-profile dome or "super" enhanced washer, providing both functional load distribution and a decorative cover.
• Material properties: Polished 316 stainless steel construction ensures durability, strength, rust-proof performance, and a shiny, attractive appearance that resists tarnishing or degradation over time.
• Related variant: A larger 2-1/2" version (SKU S-0016) exists for 3/8" fasteners, following the same design principles.

It is not a standard flat washer but an upgraded, aesthetic variant often marketed specifically for visible applications where appearance matters alongside function.

Functions and Uses

Primary Functions:

• Distributes the load of a fastener (bolt or screw) over a larger surface area to prevent pull-through, crushing, or damage to the mounting material (e.g., fiberglass, wood, or metal panels).
• Provides a decorative, finished appearance to hide or enhance the look of exposed fasteners.
• Offers a countersunk-like recess that allows the fastener head to sit flush or slightly recessed for a cleaner, more professional installation.
• Enhances corrosion resistance in demanding environments due to the 316 stainless steel material.

Common Uses (primarily in marine and boating applications, but adaptable to other outdoor/exposed settings):

• Securing and decorating visible hardware on boat hard tops, T-tops, bimini frames, radar arches, or canvas mounts.
• Fastening engine boxes, hatches, deck plates, rod holders, or other marine accessories where the washer remains exposed.
• Covering or finishing screw/bolt heads in fiberglass, teak, or polished surfaces on boats, yachts, or docks for an upscale, polished look.
• General marine deck hardware installations requiring both strength and aesthetics (e.g., railings, cleats, or trim pieces).
• Any application needing a larger, decorative washer in corrosive outdoor environments, such as coastal structures, RV exteriors, or architectural metalwork (though it's most commonly associated with marine use).

This washer is ideal when you want the security of a functional washer but prefer a more elegant, eye-catching finish rather than a plain flat washer. It's commonly sold through marine hardware suppliers like Whitecap, Defender Marine, or similar outlets. If you're installing it, pair it with matching 1/4" 316 stainless steel bolts or screws for full corrosion resistance.

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