Acorn Nuts

Acorn nuts, also known as cap nuts, feature a domed fastener head which protects screws and bolts from stripping, allowing for reuse after maintenance.

Material

Aluminum

Aluminum fasteners are a light weight alternative to steel fasteners. Aluminum is soft, non-magnetic, and corrosion resistant. These fasteners offer good electrical and thermal conductivity, and a good strength-to-weight ratio.
Brass

Brass is a soft, non-magnetic fastener material that offers corrosion resistance, heat and electrical conductivity, and cosmetic appeal. Brass fasteners may be found in electronics, plumbing, and marine applications.
Nylon

Nylon is a lightweight, wear resistant, non-magnetic, non-conductive, corrosion resistant fastener material often used in electronics applications. Nylon fasteners are commonly made of nylon 6/6, which is generally able to withstand oils, greases, and solvents. Many nylons melt rather than burn and have the ability to self-extinguish. Nylon fasteners may swell from moisture absorption, degrade under UV exposure, or fail in high strength applications.
Stainless Steel

Stainless steel is steel combined with alloying elements, principally chromium, to enhance corrosion resistance and impart other desired properties depending upon the alloying elements in use and their proportions. Many stainless steel fasteners are non-magnetic or less magnetic than regular steel fasteners.
Steel

Steel is the most common fastener material due to its strength properties. Unalloyed steel may be surface treated to enhance corrosion resistance and other desirable properties.