The Can Seam Scale with English units on one side and metric units on the other, has several uses.
Basically, it is a handy pocket ruler calibrated in thirty-seconds of an inch from zero to six inches, and in tenths of a centimeter (millimeters) from zero to 15.2 centimeters.

1. The tapered end of the scale may be used to scrape compound from the channel and curl of the end in order to determine film weighls.
2. The scale is also used as a gauge for measuring the curl height of a can end. This is done by taking a 2 inch (50.8 mm.) stack of ends, which will just fit in the 2 inch (50.8 mm.) long slot of the scale, and then counting the number of ends in the stack. Most can makers have specifications for the maximum and minimum number of ends for a two inch stack, which is a function of the curl height, the can end material and its thickness. The specification varies between aluminum and steel/tinplate, between beer/beverage ends and sanitary ends, and to some degree between one diameter and another.
3. The remaining slots or notches in the scale are useful as ”go-no-go” gauges for estimating seam thickness, length, and body and cover hook lengths, The seam scale is in no way designed to replace the can seam micrometer or the countersink gauge. The seam scale is used oniy for estimating or approximating some can dimension measurements. For the accuracy required in quality control and trouble shooting procedures, measurements made with the countersink gauge, can seam micrometer or seam projector are required.