Please consider that Hartz flea drops kills many cats/dogs every year as their flea drops is 80% weedkiller (which was banned from use years ago)

Whatever you do please read http://www.hartzvictims.org/ and goggle for other Anti-Hartz sites before buying their products.

Personally I would not let my cats nearer than 10 feet from any Hartz product, even a freebie.