A case for holding, protecting, yet allowing easy linear access to a keyless entry device, the case comprising an open ended enclosure with a springlike element provided to frictionally hold the device securely yet slidably within the case. In this inexpensively manufactured brush head attachment according to the present invention, said metal ring is a die-cast member. Facing panels are removably attached to support brackets mounted on the vertical supports. A plurality of layers is deposited over a remaining portion of the gate contact layer and insulating layer, which include a gate insulating layer, a channel layer, and a metal film. A vent valve assembly is operatively connected to the high pressure gas supply line, the vent valve assembly being operable to vent gas from the high pressure supply line immediately upon operation of the operating cut-off valve to cut off high pressure gas to the Joule-Thomson cryoprobe.