Looking For Air Tanks

RFQ Description

Hello - I have questions about an air tank made for Hitachi (now Metabo). Info from the specification plate: Manufacturer's Serial No. A*******1 Year Built 2017 Note: the "Send Your Inquiry Direct To This Supplier" will not let me paste photos. - What’s the size/diameter of the inspection plug (metric or SAE). There are two inspection plugs - one at each of the tank, near the tank's bottom. See photos. - Which thread pitch does it have (metric or SAE) - Which size wrench or socket is needed to remove the plug (metric or SAE). Note: The end of the plug with the six sides has a lot of gray factory paint on it. The paint has increased the size of the plug. That’s why I’m trying to learn which size wrench or socket fits the plug. 1. 2. The threaded steel plug is similar to this one. 3. My air tank 4. End of tank showing threaded inspection plug 5. Plug encircled by yellow circle 6. Photo showing thick factory gray paint on plu