I have two cats and ordered the VIC package with the 4 inch rails hoping to cut down on the loss of granules. The rails didn't seem to make a difference and granules continue to be everywhere, upstairs and down. Probably should have ordered the dome. Anyway, I'm having to buy more granules as the VIC package ships in four separate orders over time which doesn't meet our needs. With all said, our house smells much better and having not to scoop is great. The product is less than a year old and has worked as advertised to date.