This Universal Micrometer should be used with optional interchangeable tips. 

It offers you the following benefits: 

• Its non-rotating spindle accepts seven forms of optional interchangeable anvil/spindle tip (including flat, spline, spherical, point, knife-edge, disc, and blade) allowing you to use it in a wide range of applications. 
• Optional anvils/spindle-tips for screw thread measurement (matching V and cone) are also available.