For a nbr 4 screw
A washer having a centrally located hole with a solid or laminated cross-section and two flat parallel bearing surfaces. The hole must be 75 percent or less than the largest dimension and the bearing surface finish is greater than 32 microinch (0.8 micrometer). The thickness cannot exceed 25 percent of the largest outside dimension. When the largest outside dimension is less than 1/4 inch or 6mm, the thickness must be 0.006 inches (0.15mm) or greater and for items 1/4 inch (6mm) or larger, the thickness must be 0.016 inches (0.4mm) or greater. The maximum tolerance is applied to dimensions and used as a determining factor. Items with separable lamination use shim. For items fabricated from ceramic or electrically rated materials by specification or industry standards use insulator (1), washer. Excludes disk, valve, graphite impregnated and lubricated items.
Classification: Washers other than lock washers, iron or steel
NSN 6610-00-038-8148
NSN 5996-01-156-4092
NSN 4140-00-128-0187
NSN 5950-01-657-3576
NSN 6240-01-485-1136
NSN 6135-01-246-0308
NSN 6685-01-137-5710
NSN 5996-01-345-7547
NSN 6240-01-379-4547
NSN 6610-00-817-8772
NSN 5910-01-271-5368
NSN 6620-01-593-0817