Mettler Toledo's Jewelry Standard (JS) carat scales feature one-touch internal calibration. Equipped with a 3-door draft shield for easy use, these scales offer high-contrast display, statistics, totaling, recall, piece-counting, percent-weighing, free factor and diagnostics. Works on battery or AC operation. Weighing modes include: ct, g, mg, kg, lb, oz, toz, dwt. Scale is Legal-for-Trade in the United States. This model JS1603C/A has a maximum weighing capacity of 1600ct x .001ct.