Replacing the vent penetrator with a camera style vacuum check

could any one inform me what the thread size is on the bulkhead connectors/Vent plugs?

On our SLR housings we have a M16 port which fits a vacuum valve and inside the housing is an pressure monitor with LED which constantly monitors the pressure, this would also remove the risk of leakage if the O-rings on the vent plugs were compromised


Most of our penetrators use an M10 thread, with a few that are M6 and one that’s M14. Our Vent uses M10.