Special Features:

Cover has two flat sides; eight threaded holes ( 6-32 unc-2b ) around circumference of internal hole; groove along small circumference; width across flats is 4.378

Properties:

A rigid or flexible item of various shapes attached to a structure for the purpose of providing access for inspection, service, replacement of components and/or adjustments or mounting operations. It is designed to be attached by means of bolt holes, slots, mounting ears, tabs, and the like. To permit access, the mounted cover requires partial or complete removal. It may include an observation window. For items permanently attached by hinges and the like, see door, access (as modified). Excludes all covers not specifically designed to provide access for the purposes listed above.