The metric system is calculated in millimeters, and the imperial system is calculated in inches.

Metric system: also known as “meter system”, “meter system”, an international measurement and constant system that entered China after the signing of the “Sino-French Commercial Charter” in 1858, founded in France.

The metric system uses units of measurement such as meters, centimeters, decimeters, and millimeters to determine length, and seconds to determine the length of time

The British system: It is a measurement system used in English-speaking countries such as the United Kingdom and the United States. British law stipulates that the British system is generally used in daily life, and commercial retail must use the metric system. In some aviation management such as flight altitude and runway length, the imperial system is still used.

1inch=25.4mm

Sometimes customers’ drawings are marked in inches, this is no problem we will produce profiles based on inches.