Does the frontline kit on ebay really work without harming my cat?

My cats have fleas and I have benn looking for good frontline prices. Ebay has some 8 month supply kits that contain one tube of frontline for XL dogs that come with instructions for how to divide up the product. I want to know if this method is effective, safe and cheap.

Frontline is VERY effective. Be sure to follow the directions and it'll work.

Frontline's a great product - as long as it's not expired or counterfeit. There are lots of fake flea treatments for sale on Ebay. They look like the real thing, but are not. You'd be better off getting the real thing from your vet - you can get the large tube and a syringe, and proper instructions on dosing your cats. Rather spend money for something both real, non-expired and properly stored than some unknown product, plus shipping, that may or may not be Frontline.