The Molex 1731120301 is a rubber bushing from the FKT, FCT 173112 series, classified as a Size 1-2A accessory. It is designed specifically for use with D-Sub backshells, serving as the cable-entry seal that protects the wire bundle where it exits the backshell. This is the part you reach for when dressing a D-Sub harness and need to close the rear of the shell against dust and strain.
This bushing is built for D-Sub backshell assemblies. The 'Size 1-2A' designation refers to the standard D-Sub shell size range it fits.
It is supplied in Bulk packaging.