Both contact points and anvils are interchangeable on the dial thickness gage. When you replace them, you will have to reset the indicator to zero. Eight different contact point and anvil combinations are possible and the manufacturer guarantees accuracy for each of these. The contact point is represented by B, C and E in these diagrams. The anvil by A, D and F. 
If you use a spherical or pointed anvil with another spherical or pointed, then you won't be able to set zero in the closed position. You will have to use a gage block to set the indicator at some other point, such as .25" for example. A selection of gage blocks is available on page 164. You will not be able to use a flat contact point with a flat anvil at the same time because there is no guarantee that they will be parallel to each other. If that is what you need, then you will have to get a thickness gage which has permanent, flat anvils. For options see page 12. 
The dial indicator has .001" graduations with a measuring range of 1/2 inch. The throat depth is about 1-1/8 inch, as shown above. This model is often in short supply. | 
