Puppybone is made from inert thermopolymer to which calcium has been added during the moulding process. Puppybone is strong and durable but the addition of the calcium, being a natural material, makes the product a little softer than Gumabone and is thus suitable for use by very young dogs whose jaws and adult teeth are still developing. Choose the largest size that your puppy can comfortably carry in his mouth and remember that as he grows he will need to progress to a larger chew device.