12129487 is a cavity plug designed for use with Aptiv low voltage automotive connector systems. This accessory is used to seal unused terminal cavities in connector housings, maintaining the integrity of sealed connector assemblies. The cavity plug features a white color and does not include a restraint ring. It is compatible with multiple Aptiv connector series including APEX 150 Sealed, CTS 1.2 Sealed, HDK 1.2 Sealed, and OCS connector families. This component is essential for automotive applications where environmental sealing and protection of unused connector positions are required.