This is one of my favorite pellet treat balls for a piglet. It's the perfect size. This rubber ball works great for dropping pellets out as well as for teething. Pigs will get 3 sets of teeth so they are always teething. I find this rubber ball to be very well made and seems to be indestructible. Circumference is 9". 

Rubber Treat Teething Ball - 9" Circumference