Magnetic, domed, single-flange glass adapters are offered with Corning 7052 Borosilicate or equivalent glass. They are fitted with expansion-matched Kovar (a Nickel-Iron-Cobalt alloy) metal transition tubes. These closed end adapters are ideally suited for high and ultrahigh vacuum applications where an optically clear glass chamber is required. They're available in four (4) glass tube sizes including 1/2, 3/4, 1-1/2 and 2-1/2 inch diameters. NOTE that glass-to-metal sealing is more of an art than a science, as such (other than tube and mounting flange dimensions) all glass dimensions are nominal, and only for reference. Glass overall lengths can vary significantly from one assembly to another.