M18 × 1.5 – hose diameter 19mm

MM to hose adapter (Metric).

A neat solution if you use common hose. Just push on the hose and lock with a standard hose clamp.
All AN fittings are hard anodized, making them highly wear-resistant. The AN fittings can be used with all available fuels such as gasoline, methanol, ethanol, and diesel. They are also suitable for use in water, air, and oil systems.