Gibraltar Z8804 M4 Extra Thick Flat Washer Black Oxide

Product Description

The GIBRALTAR Z8804 is an extra thick flat washer designed for use with M4 metric screws. Manufactured from 1010 case hardened steel with a black oxide finish, this washer provides a durable load-distributing surface between a fastener head and the mating workpiece. The extra thickness of 2mm adds rigidity and resistance to deformation under clamping loads compared to standard flat washers. With an inside diameter of 4.3mm and an outside diameter of 10mm, it fits standard M4 hardware. The black oxide finish offers mild corrosion resistance and reduces light reflection. Typically installed by mechanical assemblers, millwrights, and maintenance technicians in industrial and equipment fabrication applications.

The Z8804 washer is suited for metric fastener assemblies where a thicker bearing surface is required to distribute clamp load, prevent pull-through, or protect softer base materials. It is appropriate for use in machine assembly, equipment maintenance, and structural fixture applications that call for M4 metric hardware. The black oxide finish makes it a common choice in applications where a low-reflectance or dark-finished fastener system is specified.

Key Features

• Extra thick 2mm profile resists deformation under clamping load
• Case hardened 1010 steel construction for strength and durability
• Black oxide finish provides mild corrosion resistance and low-reflectance appearance
• 4.3mm inside diameter fits standard M4 metric screws and bolts
• 10mm outside diameter distributes load over a wider bearing surface
• Metric dimensioning suitable for metric fastener system assemblies

Compatibility

Designed for use with M4 metric screws and bolts in metric fastener assemblies requiring an extra thick flat washer.

Installation Notes

Installation is performed by hand or with standard hand tools as part of a fastener assembly. Ensure the washer is seated flat against the bearing surface before applying torque to the fastener. Power down or de-energize equipment before servicing fastened assemblies on live machinery. Follow applicable equipment manufacturer guidelines and relevant codes for fastener assembly in your jurisdiction.