I use one for my insulin resistant horse that has a voracious appetite. He would have his hay gone, and banging the door for more, before lights out if I didn't put his hay in a slow feeder. I also have a scale at the barn to weigh his hay.
I tie it securely in his stall so it hangs over his hay tub. They should be hung so the horse has to eat "down" as much as possible because that's the natural way for them to eat.
He is also barefoot so can't get a hoof hooked in the net if he were to paw it - something else to think about
A side note on fast and always hungry eaters like this:
My vet said I probably saved this quiet, laid-back guy from an ulcer
He very kindly took the time to explain how it all works but I couldn't remember it al. The basic reason a fast eater can get ulcers is related to the acid level in their digestive system. Somehow when they think they're starving the acid level rises, there's nothing in their stomach and that can possibly cause ulcers.
Hopefully someone that is much smarter than me can explain it better, but that is from the vet's mouth when he did physicals on my crew two weeks ago
I bought this one and it works ok for what I need Saddles Tack Horse Supplies - ChickSaddlery.com Slow Feed Small Mesh Hay Bag
My horses come in at night and out in the daytime and this guy goes out with a grazing muzzle - the Tough-1 Easy Breathe, also from Chick's
Gigem88, you might have a market for the slow feeders if you start making them - there's a lot of overweight, fast eating horses that could use them:)