Yellow Jacket 49202 3-1/8", Blue Compound, 30"-0-120 Psi, R-12/22/502 Certified Gauge (°F) with 1% accuracy (Class 1) calibration. Large 3-1/8" gauges are housed in a red or blue steel case with front recalibrator screw. High visibility colored temperature scales are easy to read through the full view polycarbonate crystal.