How to treat the nozzle model of argon arc welding?

A box of argon arc welding guns has 10 porcelain nozzles, which are cups 1 to 10 respectively. According to the caliber, the larger the number of cups, the larger the caliber. The first cup is the smallest, and 10 cup is the largest. Some welding positions, big porcelain mouth can't get in. At this time, you need to use a small porcelain mouth. It is easier to weld large porcelain nozzles in some places, so it is necessary to use large porcelain nozzles. Generally speaking, it is distinguished by caliber.