I recently purchased a spring inside caliper for taking accurate measurements in my woodworking shop. After I put it to the test, i was blown away at how precise my measurements were. This tool is essential for anyone who needs precise measurements for their projects... The best part about it is the durability this caliper is built to last with its hardened and tempered points. The only con I can think of is that it may be a better fit for those who are trained in using calipers. Overall, a great investment in industrial and scientific tools that are built to last..