Fowler 52-229-204 52-229 Series Swiss Style Outside Inch Micrometer, 3-4" Measuring Range, +/- 0.0002" Accuracy, 0.0001" Graduation Outside micrometer with choice of measuring range and flat anvil/spindle pair for general purpose measuring Vernier scale has 0.0001" graduation intervals for precise readings Hardened and precision-ground anvil and spindle have 0.256" diameter micro-lapped carbide measuring faces with 0.00005" parallelism on 0 to 1" micrometers and 0.00003" flatness for accurate measurements Friction-style with ratchet stop applies constant force for repeatability between users and is suitable for one-handed operation Heat-insulated frame helps reduce temperature-related expansion or contraction and isolates heat from the operator's hand