I bought the gun kit and a few of the extensions a couple years ago and it works great. Just wish my vehicles would have had that protection since new. It doesn’t kill deep rust once it’s started but it does slow it waaaaaay down. A good example is my 99 Dodge 2500, it has 240k NY snow country miles on it and it started bubbling above the rear wheels like all dodges do because of the foam in the seam. I soaked the area with fluid film 2 winters ago and it hasn’t spread at all. Pretty impressive. I will say the stuff smells a little weird but it’s only strong right after coating it. I apply it every fall.