Royal Canin Intense hairball variety
Fantastic results. My five cats go outdoors but during winter months tend to hog the sofas and anywhere near a warm radiator. A few of them developed a nasty cough which was worrying, and they all kept coughing up hairballs. My vet recommended changing to a Hairball variety of dried food.
As we already were using Royal Canin, I tried your Intense Hairball. Results very good - no more coughing. May swap back to usual variety once they've shed winter excess fur. Unfortunately can't do much about them sleeping on the sofa!