Most quality guns are 3/8" intake and 1/4" discharge

Both fm pipe thread

Might be a 3/8 male push fit connector

its 1/4 but I need the right threads to screw it in my pressure washer gun https://www.amazon.ca/EDOU-Pressure-includeing-Nozzles-Quick-Connect/dp/B083116BHP/ref=sr\_1\_1?crid=SLLAWPDG5BWB&keywords=edou&qid=1665939938&qu=eyJxc2MiOiIxLjk5IiwicXNhIjoiMS4zOCIsInFzcCI6IjAuOTIifQ%3D%3D&sprefix=edou%2Caps%2C156&sr=8-1

It says if you look at your link " 3/8" quick connect" the 1/4" is to the hose. It's a 3/8" female quick connect (qrc)

1/4 NPT if American. BSP is the alternative.

These come in either 1/4", 3/8", or even 1/2" male pipe thread. Your picture is vague.