Dunnage bags are usually inflated with an adapter that take high-pressure air from a compressor and converts it to high-volume low-pressure air.
This adapter is useful when you have a supply of low-pressure high-volume air (eg from a bouncy castle blower) instead.
There's also a tool to let you open the built-in valve in the dunnage bag.
Only tested one one brand of bag, from Exporta.
Assembly requires a cable tie to hold the latch parts onto their pivots (don't do it up too tight) and a rubber band or loop of bungee to hold the latch closed. You also need 4 short self-tappers to hold the spigot into the adapter.
The author marked this model as their own original creation.