These micrometers reach over the edge of sheet metal and take measurements away from the edge toward the center. Also for other gaging jobs where a deep throat micrometer is needed. Rounded anvil on 1" (25mm) size gives a point contact for more accurate gaging; ?at anvil is also available. The 1/2" and 13mm micrometers have satin chrome frames. Anvil: Flat. Graduation: .001". Ratchet Stop, Lock Nut