Fowler 52-401-221-1 Inch Series Interchangeable Anvil Micrometer Set, 0-6" Measuring Range, 0.001" Graduation Intervals Outside micrometer with choice of measuring range and flat anvil/spindle pair with interchangeable anvils for general purpose measuring requiring a wide measuring range Vernier scale has 0.001" graduations for precise readings and accuracy of 0.001" on 0 to 1" micrometers for accurate measurements Carbide-tipped anvils provide wear resistance and are fitted with an adjusting collar to set the overall dimension Hardened, ground, and micro-lapped spindle thread provides smooth movement, accuracy, and long life Ratchet stop applies constant force for repeatability between users