This picture shows how keys are duplicated here. This man sits on a chair near the curb in front of a hardware store, using the short wall as his work desk, takes a key blank and using the metal file in his hand, hand-files the key to match the key I gave him to be duplicated. He uses his micrometer on his lap to get the depth of each cut the same as on the original. It takes 5 to 10 minutes. The duplicate keys work great!