Instrument body with 5 sets of bushings. Contributes to longer brass life
Improve the accuracy of measuring bottlenecks with the measuring tool
Small screws on the comparator body can be adjusted to hold the bushings in place
More accurate measurement of changes in brass firing or sizing for improved safety
How to determine the proper bushing diameter: add the neck diameter and shoulder diameter and divide that number by two, using the bushing closest to that number