A compressed gas cylinder valve seal comprising a non-metallic seal substrate having a top surface, and a bottom surface connected to one another along a circumferential skirt, an elastomeric material overmold retention channel passing completely through the seal substrate, an elastomeric material overmolded onto the top surface and the bottom surface and filling the elastomeric material overmold retention channel, and a gas passageway passing axially, completely through the non-metallic seal substrate.