The Amphenol AC-NUT-METAL is a replacement backshell for Amphenol's AC series XLR cable connectors: the rear part that screws onto the connector body and grips the cable. Amphenol's drawing describes it as an AC series machined nut assembly, a brass nut fitted with a black 7 mm grommet, about 49 mm long with a 19.3 mm diameter. It is used by technicians and hire companies to repair AC series XLR connectors whose rear shell has been lost, cracked or damaged, or to replace a coloured plastic nut with the more durable metal version, without having to re-terminate the whole connector. It fits the AC series (for example AC3F, AC3M, AC4F, AC5F) rather than other brands. Amphenol lists it as a 100 pack in its own catalogue; check the pack quantity on this listing before ordering. Coloured plastic versions (AC-NUT-BLU, -BRN, -GRN and others) are available separately for colour-coding cables.