Terminology can be confusing. The terminology often used here on the Forum says there are two fill ports. There is a high-pressure garden-hose port, and a low-pressure bucket-fill port. The high pressure port
does not fill the tank - only the bucket fill port does that. Perhaps this diagram from my Tech Stuff Album will help.
https://www.trailmanorowners.com/for...&pictureid=435
Assuming you are asking about my 90-degree PVC adapter, its purpose is to enable you to fill the the tank through the bucket-fill port, using any piece of hose with a garden hose fitting on one end. That hose can come from a high pressure source (a spigot), or from any low-pressure source that can have a piece of hose attached. For example, this low-pressure source might be a hand-held funnel into which you pour water, a siphon from a water container set high up on a stepladder, or a kayak bilge pump drawing water from a bucket on the ground. I did the funnel thing (hated it - the container of water is heavy and you need at least three hands), then the siphon thing (hated it less, but you still have to hold the heavy bucket up high), and finally went to the bilge pump approach (not too bad, since the heavy container doesn't have to be lifted). The right-angle piece does two things when you push it into the port. It holds the device in place so it doesn't fall out, and it straightens out the first few inches of the slinky hose inside the TM so water doesn't splash back at you.
Hope this helps.
Bill