Short nozzle with small hole diameter (3mm)
The "short nozzle"; which is the one with a 3mm diameter hole is mostly used for laser cutting materials that are likely to cause a lot of smoke, like wood. As a result of the small opening, the flow of air is directed into the kerf, releasing any emerging smoke and cutting the gases, which protects your laser machine. This nozzle is not suitable for dust-intensive materials, like plastic and rubber. The engraving dust tends to settle at the opening of the nozzle and may block it. This may then cause burn holes in the lens.