This adapter allows a smaller conical plug (in this case, a cheap Harbor Freight blowgun) to fit inside the larger Intex air ring hole so that you can use an air compressor to fill up the ring. If you have a different size plug to fill or a different size blowgun tip, you may be able to use the customizer function to modify the sizes (but I haven't tested this functionality).
Make sure you set the PSI on your pressure regulator to a low number so that you don't accidentally over-inflate the ring and cause holes.
Update: if you would rather use an adapter that screws directly into the blowgun, see http://www.thingiverse.com/thing:1630706
Printer:
Monoprice Maker Select
Rafts:
No
Supports:
No
Resolution:
0.25
Infill:
10%
Category: Outdoor & Garden