The set contains 5 brass and 5 aluminum grain weights for accurate weighing of delicate items. A grain is a unit of weight equal to 0.06479891 gram, in the avoirdupois systems. It is part of the Imperial system of weights and measures. An avoirdupois pound equals 7000 grains. Verification marks of the weights includes: A Victorian standard numbered stamp of a royal crown over cipher VR and the number 2 for London City (see The Lower left picture). These stamps date from between 1879 and 1901.