Jeweled Movement gives you the ability to see variations in measurements as small as .0001". A hardened measuring tip adjustable within a 240° range is combined with top, front and rear dovetails to give you greatest flexibility. Two ranges and accuracy - 0-.030"(.0005" reading) and 0-.008"(.0001" reading) in either direction. 5/32" and 3/8" dovetail to post adapters are included in the storage case to make your setup easy.