I use a rubber bit for Pony. He likes it, but he tends to chew it up so I end up buying a couple of them a year. I was looking for another one and everyone was sold out. I finally found a place to order it from. In talking to this place, I learned that many bits are currently in short supply due to shortages of rubber and metal. I thought this was really interesting, so I thought I'd pass it on. If you're shopping for a new bit, this may impact you.