This interface is a connection between the hose of the Mistral SUP hose. To fill the big amount of air with a electrical pump. For the high pressure the hand pump is still needed but the electrical pump saves time. This part is made for a runacc pump but I guess it fits for a lot of other of another brand.
Printed with Amazon TPU. The same setup will also work with Saintmart TPU.
The author hasn't provided the model origin yet.