A flat metal or plastic item of various peripheral shapes having a solid (not laminated) cross-section. It is designed to maintain a predetermined distance between two surfaces. For round items without a hole having a solid rectangular cross-section use disk, solid, plain. For round or hexagonal items with only one hole centrally located and with the length (thickness) exceeding 25 percent of the outside diameter or distance across peripheral flats, see spacer, sleeve. The thickness between the two parallel bearing surfaces must be 0.006 inch, (0.152 mm) or more for items less than 1/4 inch (6.35 mm) across the peripheral diameter, or smallest overall outside dimension, or must be 0.016 inch (0.406 mm) or more for items 1/4 inch (6.35 mm) or greater across the peripheral diameter or smallest overall outside dimension. For items with a thickness less than those indicated above, see shim. For items with one hole centrally located conforming to the above dimensional criteria use washer, flat or spacer, ring as applicable. When thickness and/or outside diameter or smallest overall outside dimension is designated as a tolerance/dimension the maximum dimension will be used to determine compliance. Excludes gasket; insulator (as modified) and mounting pad, electrical-electronic component.
Dept. of the Air Force 
Dept. of the Navy NSN 6130-01-421-2705
NSN 6620-01-470-6479
NSN 5999-01-182-4929
NSN 6645-00-583-0066
NSN 6150-01-475-8690
NSN 5999-01-571-9446
NSN 5965-01-529-9938
NSN 6110-01-010-9310
NSN 5945-01-213-2467
NSN 5965-01-053-7168
NSN 5915-01-055-8592
NSN 6645-01-512-8472