The LSU49-5V is an analog controller for wideband lambda probeLSU4.9 to give a signal between 0 and 5V proportional to richness.
Its very small size is that there is no housing. The electronics are under the boot (Raychem 202K132) on the rear of the connector.
The same boot is filled with resin to obtain a better mechanical strength and protection against moisture.
Its implementation has resulted in the connection of four wires. The choice of connector is at the customer's convenience.