OIML Class F1 – Appropriate for calibrating high-precision top loading balances with a readability as low as 0.01 g to 0.001 g.OIML Class F2 – For calibration of semi-analytical balances and for student use.All Weights with F1, F2 class type are listed in the link below :Cylindrical Knob Type WeightsMilligram Sheet Metal WeightsRectangular Weights Inquire Now