Dear Mr. Hwang, I have found your Vernier caliper program very useful for checking machine operator knowledge of use the caliper. Also we've organized a measurement training for our production personnel in which we had used the program to check their skills. Thank you very much for your efforts in spreading the physics all over the world! Kind regards Janusz Ciesla MSc, Mech. Eng. ULTRATECH POLAND www.ultratech.pl