While most of the world operates on the Metric System for measurements and standard fasteners, the United States of America uses the Imperial System. The best machine shops will be comfortable working from drawings that use both Metric and Imperial units. Choosing a shop that is familiar with Metric and Standard means they have tooling on hand, which will keep your costs lower. You also ensure your units are converted correctly, the right taps and dies are used, and the right measurements taken during the quality control process.