I have actually used this stuff for RUBBER suspension bushings ONLY (I would NOT put it on rubber brake lines, and would be hesitant to use it on steering rack/CV joint bellows).
I buy the liquid bottle and pour it into a pump spray bottle.
DO NOT put too much of this on or it WILL turn the bushing you are trying to swell/quiet to MUSH.
Just wet it slightly and let it soak in.
It DOES work for me, especially on the front lower control arm rear bushings which are a PAIN to replace.