Frank....I buy Iams Hairball Formula dry catfood for the girls. You will not believe the difference! There are two or three different ones: one is original in the orange bag, one is for indoor cats that is a weight control formula in a tourqoise bag, and one is for adult cats in a dark royal blue bag. You have to look on the bag to make sure it's says "hairball formula", because each one of those - in the same color bag (

) - is not "hairball formula". You would think they would use different color bags to differentiate the formulas, but that would be too easy. They are also the same price regardless of formula.
Even with 4 of them, inside all the time, I don't average even 1 hairball a week. When there is one, it's a different consistency... about the shape of my little finger, firm, and lifts right up with basically no mess, and I have light sand colored carpet.
I can always find it at Walmart. Sam's used to carry the big bags, of the plain and I would just mix a bag of hairball formula into it, which works, but not quite as well. They still carry Iams dog food but stopped the cat food.

KMart quit carrying it, Target usually has it, a couple grocery stores do - but it's a couple dollars more at the grocery, and about $4 more at Petsmart.
I have one of those feeder trough containers and it's out all the time. I fill the container about once a week, and it's $7something for the smallest bag and it fills the container full. The largest bag, when I can find it, is about $22, and it will fill the container 4 or 5 times.
Oh...it does make them drink a lot of water too, which is very good for their urinary tract. I've used Iams for over 20 years, ever since I almost lost one to a severe/kidney bladder infection that was so bad, the vet said if she had been a male cat, he couldn't have saved her. The vet told me then to use either Iams or Science Diet, and at the time I could only find them at the pet store. Iams was cheaper and it went into the grocery store first, so I just stayed with it.