its a gunner position ain't it?
EDIT: how do i use it?

Nope... its auto puffy in the WW1 Arena...
Well wood, fabric & paper tear-up way easy, so even a near miss is a hit. 
hehe... it works against WW2 planes with the same lethality. I set up a custom arena for ww2 planes using the ww1 map... forgot about the puffy ack. Flew too close to an opposing base in a Jug, and it was BOOM... back in the tower.
