These ODU Medi-Snap In-Line Receptacles require a Back Nut which come in a choice of colours, see stock number 706-0330 typical.
MEDI-SNAP
The ODU Medi-Snap range are miniature cylindrical connectors with Push-Pull-Locking in Plastic suitable for medical appliances. They are polarized for the number of ways and can be colour coded as required.