Gage blocks were first introduced in the 1890s by a Swedish armorer inspector. Such blocks are made of steel or ceramics. They are fine grinded and lapped to match exact measurements. The length value that is assigned to each block includes the exact length of the block as well as the layer of oily film. The size error is absolutely minimal, and is not considered when assembling several blocks together. These utilities are required for quality control of tools or manufacturing processes, or in special laboratories. MegaDepot offers block sets as well as standalone blocks, needed for replacement of damaged ones.