These custom invar 36 socket head screws were manufactured domestically for University of Rochester with a broached socket drive for faster turnaround.  Invar 36 material is typically used in applications where dimensional changes must be limited or minimized in extreme temperature variations - thermal expansion is at a fraction of the typical carbon steels.  We have provided a number of parts in this material and often the socket head bolts incorporate a vent across the full length the part as well, depending on the exact application.  Full certs were provided with the parts.