Highest accuracy (1 ppm/yr) and stability (±0.5 ppm/yr typical) of any resistance standard Lowest temperature coefficients (< 0.1 ppm/ºC) Available in 3 models: 100Ω, 1000 Ω, 10,000Ω. Has remained the foremost resistance standard, with no equivalent, for over 35 years 5 Year Warranty Included