???????Tempco's connection heads are gasketed to seal against moisture, dust and corrosive or hostile atmospheres.Screw covers are attached to body with a plated chain.Covers have lugs for tightening or loosening with a screwdriver or wrench.Available in single (2-wire) or duplex (4-wire).Tempco's connection heads are available in die cast aluminum, Bakelite and cast iron in a variety of sizes from miniature for confined areas to the large universal head designed for heavy process and industrial applications. See Sensor Accessories for complete details.Pipe nipple is galvanized steel.