Its highly reliable drive mechanism, the Honeywell 85000 Series features an odometer gear train and accurate quartz crystal timing to provide enhanced performance. UL/CSA recognized, with a variety of mounting styles. An improved odometer gear train, plus snap-together chassis, fits into a shock-proof, totally sealed case often resistant to many acids and solvents. All parts are in-process inspected. Every meter must pass a 100 percent function, burn-in, and timing accuracy test before shipping.