Rubber shell connectors also called Packard connectors. Connectors are part number MS27144-3 (female electrical connector/male rubber shell). Made in USA. Ozone resistant rubber.
Ribbed shell style is often used with gauges and other applications to call out importance of connecting to correct mating connector. On gauges the ribbed shell is the sending unit wire. The ridges in the rubber are a visual aid only.
Sold in packs of 10 (example if you need 30 enter 3). Terminal ends can be soldered or crimped on to the wire. These are made for 14 AWG stranded copper wire. Connectors are used on many Military vehicles but are good for custom projects too.