Aqua Marina Boston Valve

A Boston valve is one-way check valve with 2 ports, which allows for easy inflation and quick deflation of inflatable items. It is used in larger inflatable products, such as inflatable boats and mattresses, to speed up the process of inflation and deflation.

As you can see in the second image, it has 3 core elements:

1. The base, which is built into the rubber tube (far right)
2. The middle part, which is screwed into the base (mid)
3. The top cap, which is screwed onto the middle part (far left)