Junk Launcher turns flak into a bunch of asteroid-like objects that linger and collide with enemies. Fire rate remains mostly the same and the pieces of junk fragment much like the asteroids already in the game and do damage based on size. Projectile size upgrades increase the number of times each piece of junk can break into.
Polluter turns flak into a passive weapon that drops fragments that do damage when collided with by enemies. The polluter changes the weapon fire arc from forward to backward between 45-180 degrees. Projectile size influences how long the fragments remain on the screen.