The OHAUS SPJ303 Carat and Gold Standard Portable Jewelry Balance is designed with mechanical attributes that guard against shock and overload to protect the weighing cell. Simple to use, the OHAUS SPJ 303 is 2 clearly marked buttons and a large LCD with clear numeric and unit indicators. Quickly zero the OHAUS SPJ303 balance or toggle through available weighing units with a quick press of a button. A calibration lock switch controls calibration access.