Stainless Steel Cap Nuts
What are stainless steel cap nuts? Stainless steel cap nuts, also called acorn nuts, are closed-top nuts with a domed end that cover exposed threads for a finished, safe look. Made from 18-8, 304, and 316 stainless, plus A2 and A4 metric, they resist rust on visible outdoor and marine hardware while protecting the bolt end and preventing snags.
Stainless Steel Cap Nuts
Standard Cap Nuts
Corrosion-resistant low-crown domed nuts in 304, 316, and metric A2/A4 stainless that cap a bolt end for a clean, finished look.
High Crown Cap Nuts
Taller domed cap nuts that cover longer protruding threads while keeping the finished, rounded look.
Extra Tall Cap Nuts
Deep-domed cap nuts that cover the longest thread projections where a standard or high crown won't fully enclose the bolt end.
Where cap nuts are worth the upgrade
Cap nuts earn their place anywhere a bolt end is visible or within reach. The domed top hides sharp threads, prevents snags and scratches, and gives a clean, finished appearance on railings, furniture, and equipment. In stainless they add corrosion resistance so the finished look lasts outdoors. Match the grade to the environment, with 18-8 or 304 for general use and 316 or A4 for coastal and saltwater exposure.
Cap nut crown heights
- Standard cap nuts: low-crown dome that caps a bolt end for a clean look.
- High crown cap nuts: taller dome that covers longer thread projections.
- Extra tall cap nuts: deep dome for the longest protruding threads.
Common applications for stainless cap nuts
- Railings, gates, and handrails
- Marine and dock hardware (316 or A4)
- Furniture and visible fixtures
- Playground and public equipment where snag-free ends matter
Pair these with matching stainless bolts, and browse every crown height and finish on the main cap nuts category.
Stainless Steel Cap Nuts FAQ
What grades do cap nuts come in?
18-8, 304, and 316 stainless, plus metric A2 and A4. A2 is comparable to 304 and A4 to 316.
What is the difference between a cap nut and an acorn nut?
They are the same thing. Cap nut and acorn nut both describe a closed-top nut with a domed end that covers the bolt.
How do I know which crown height I need?
Match the crown to how far the bolt protrudes. Use standard for a flush bolt end, high crown for longer projections, and extra tall for the longest threads.