This kibble ball will keep your cat busy and prevent him to eat too fast (and ask for more). The ball has facets (it is not a perfect sphere) which prevent the ball to roll perfectly straight. This is a 88mm diameter ball, pierced with 4, 6 or 8 holes in each half. I have also added two halves without holes, so that you can pierce them as you like. The holes are 10mm diameter, which was sufficient for my dry food. You will need one 'normal' half and one 'with lip' so that they mount together. You will also need a 84x4mm diameter threaded rod, and two nuts (along with their covers) to secure the ball. The nuts should be glued on each half of the ball, then covered. I glued one extremity of the rod to one of the nut, as it makes the other half screwing easier.