Those are Acecare tanks - made in China and they are fine quality. Iorman is the company name they use on ebay and amazon, as far as I can tell. I have a 6.8L bought directly from Acecare off aliexpress. Most of them are not DOT-certified but if you are filling yourself, that's not an issue. They usually have the Euro standard valve thread instead of the US one, though lately I've seen them advertising US standard threads as well. Also, in the middle pictures you can see the sticker - that tank is 3L.
@rotowag - ymmv, but I believe dive shops and fire stations are not supposed to fill them unless they are DOT-cert (and up-to-date hydro tested). Thane makes a good point - 3L won't give you too many fills before needing it refilled. If you don't have a compressor and don't want to buy (or maintain) one, then I'd probably recommend buying a DOT-cert tank for your fills. As you no doubt have read on this forum, you can get a used tank off ebay. Alternatively, here's a 6.8L tank, DOT-cert, with everything you need refill your gun (you may need an adapter to connect to the dive shop filling station, depending on what they have in-house). It's $360 with free shipping. https://www.aliexpress.com/item/Acecare-Promotional-event-4500Psi-300-Bar-CE-certification-6-8L-DOT-for-airsoft-gun-and/32874744803.html