Alkali Scientific™ W1005-1000 M1 Grade Calibration Weight, 1000g from economy to expensive analytical models, require routine calibration and accuracy confirmation. All individual weights are supplied in protective, screw capped plastic containers. We offer both F1 and M1 class individual weights. Alkali Scientific™ W1005-1000 M1 Grade Calibration Weight, 1000g is supplied with an individual Certificate of Verification confirming that the weight(s) meet OIML regulations and tolerances for the specific weight class.