Gibraltar Z8952H Square Flat Washer 3/8 in Bolt Black Oxide

Product Description

The GIBRALTAR Z8952H is a square flat washer manufactured from case hardened steel with a black oxide finish. It is designed for use with 3/8 inch bolts and provides a 2 inch square bearing surface to distribute load across a wider area than standard round washers. The black oxide finish offers mild corrosion resistance and reduces light reflection in the installation environment. With a 7/16 inch inside diameter and 1/4 inch thickness, this washer suits heavy-duty fastening applications where increased surface contact and resistance to deformation are required. Licensed tradespeople and maintenance professionals install these washers in structural and mechanical assemblies.

This square flat washer is suited for use in residential and commercial construction, mechanical equipment mounting, and structural fastening applications. It is commonly used where standard round washers would not adequately distribute clamping load or where a flat, stable bearing surface is needed against wood, metal, or composite materials. The case hardened steel construction makes it appropriate for higher-load fastening scenarios encountered in HVAC equipment mounting, electrical enclosure installation, and general trade work.

Key Features

• 2 inch square bearing surface distributes bolt load over a wider area than round washers
• Case hardened steel construction resists deformation under clamping load
• Black oxide finish provides mild corrosion resistance and low-reflectance appearance
• 7/16 inch inside diameter fits standard 3/8 inch bolts
• 1/4 inch thickness adds rigidity in high-load fastening applications

Compatibility

Designed for use with 3/8 inch bolts. Suitable as a load-distributing flat washer in standard fastening assemblies requiring a 2 inch square bearing surface.

Installation Notes

Install using standard hand tools appropriate for the bolt size. Ensure the mating surface is clean and free of debris before seating the washer to maintain full bearing contact. Follow applicable mechanical codes and torque guidelines specified by the equipment manufacturer or structural engineer for the fastening assembly.