The VHP10x represents an essentially Zero Temperature Coefficient Resistor type of resistor. This oil filled hermetically sealed device makes unique use of foil on ceramic in such a way that self cancelling responses to temperature are produced by combining equal and opposite effects.
This product is sold only in hermetic packages because applications requiring this level of temperature stability require humidity stability as well. The value of the hermetic enclosure over the molded part is in the long term performance. The hermetic sealing prevents the ingress of moisture and oxygen, while the oil acts as a thermal conductor.