The SPCSM calipers are for measuring the thickness of tops and backs. This extremely well made caliper is manufactured in the USA with a dial gauge made in Germany. The gauge measures up to 30mm in 0.1mm increments. The body is CNC machined powder coated aluminum. The throat has a 8 1/4" capacity.
The SPCM has a deeper throat than the SPCSM to measure wider tops or measure farther across regular tops. Notice that the thumb lever pulls the dial measuring pin from the top so that there is no interference between the caliper frame and the wood being measured. This die-cast aluminum tool measures in .1 mm increments mm with a maximum opening of 30 mm.