AND Ion BM [BM-300] Analytical Balance, 320g x 0.1mg - 90 mm Ø with Internal Calibration. The A&D Weighing BM-300 Ion BM Series Analytical Balance, 320g x 0.1mg features auto response adjustment allows balance to auto or manually stabilize FAST, MID, SLOW depending on draft & vibration influences. The BM20 auto self-calibration will detect changes in ambient temperature and auto calibrate.