The inside micrometer is the most direct measuring tool used for inspection . The total length of the inside micrometer is itself the overall length being measured. The inside micrometer is a much more accurate measuring tool for inside measurement than the vernier caliper.  Rod Inside Micrometer Sets are the most popular inside micrometers because of their lightness, ease of use, and range. They are very useful for measuring inside diameters of cylinders and rings and measuring parallel surfaces,

Order No	Range(mm)	Accuracy
IM-220301	100-125	0.006
IM-220302	125-150	0.006
IM-220303	150-175	0.007
IM-220304	175-200	0.007
IM-220305	200-225	0.008
IM-220306	225-250	0.008
IM-220307	250-275	0.008
IM-220308	275-300	0.009
IM-220309	300-325	0.009