Abstract: An improved sender module closure system for providing a reliable, sealed interface between a sender module and a fuel tank at the access port thereof, includes an interfacing ring set composed of a base ring and a helmeted lock ring. The base ring is permanently connected to the fuel tank at the access port, and has a plurality of upstanding lock fingers. The helmeted lock ring is a separate piece, composed of a lock ring component and an integrally connected helmet component. The lock ring component has a plurality of finger apertures, one for receiving each lock finger. The helmet component protectively covers the sender module and has helmet apertures for external access to connectors of the sender module.