There is a groove 0.281 inches wide and 0.371 inches deep
A tubular shaped item with a round or hexagon peripheral shape having two flat bearing surfaces perpendicular to the axis of the centrally located hole. It is designed to maintain a predetermined distance between assembled parts. The item may be with or without flange(s) of any peripheral shape. The overall length must exceed 25 percent of the outside diameter or distance across peripheral flats of the body. (when the length, outside diameter, and/or distance across peripheral flats are designed as a tolerance, the maximum dimension will be used to determine compliance). For items having other than a round or hexagon peripheral shape, see spacer, plate. Excludes items with lubricating features, see bearing, sleeve and bushing, sleeve. See also bushing, tapered; spacer, ring; washer, flat; and washer, (as modified).
Classification: Other articles of iron or steel not wire nesoi
NSN 5930-01-188-2618
NSN 5990-01-247-5439
NSN 5905-00-277-7439
NSN 6105-00-145-2607
NSN 5925-01-646-0195
NSN 5945-01-347-0531
NSN 5945-01-050-9172
NSN 5910-00-579-7752
NSN 6645-00-124-9939
NSN 5975-01-426-1518
NSN 6220-01-421-4448
NSN 5950-00-270-3063