External micrometer with tungsten carbide tipped anvils enamel frame with lightweight workshop design the thimble and sleeve have a satin chrome finish supplied in a sturdy plastic case and suitable for all external measurements in either workshop or inspection departments 103 131 ratchet graduation 00001in 103 129 ratchet graduation 0001mm103 137 ratchet graduation 001mm103 138 ratchet gradation 001mm