Marine Depot Maintenance Command (MDMC) is requesting a replacement Cubis Mass Comparator for use in its Metrology and Calibration Laboratory. The mass comparator is required to calibrate Class C weig... Marine Depot Maintenance Command (MDMC) is requesting a replacement Cubis Mass Comparator for use in its Metrology and Calibration Laboratory. The mass comparator is required to calibrate Class C weights and higher-precision standards used to support depot maintenance operations.