The 5615-12 is a Platinum Resistance Thermometer (PRT) with an Inconel 600 sheath that's 305 mm (12 in) long and 6.35 mm (0.250 in) in diameter. It is a secondary reference temperature standard designed to bridge the gap between the highest laboratory standards and industrial or second-tier lab locations. It has accuracy of +/- 0.012 *C at 0.01 *C.