Hose barb for hose with an inner diameter of Ø9 mm

With 3/8 BSPT male thread on the other side.

The male thread is tapered.
The coupling housing is made of brass.

You can screw the coupling onto a 3/8 BSP outlet and slide a hose with an inner diameter of 9 mm over it.

This coupling is easy to use by sliding the hose over the barb until it is firmly in place.
The hose can be additionally secured with a hose clamp if necessary.
 

Abbreviations:

BSPT: British Standard Pipe Tapered, also known as gas thread. (Tapered = conical/reducing)
 

More information on hose sizes and threads can be found here: About Threading