asa
that thingy thing not only holds your bottle of air but is slideable back and forth givng a different reach for you holding your gat ( gun ) when holding your gat grip the bottle should end at the crease of your forarm, some of these thingy things have on and off so you can take the gat apart because it`s hard to take the bottle off when the air is on, They are called an A S A or very often called an OOPS , there are good and bad makes , so make sure you get it right, as from these the macro line ( hose ) can go from the side or direct feed from the front , your choice ! although going forward is better for you to hold left and right handed