Himalayan Dog Chews are made by boiling yak and cow milk and then dried for several weeks to create a hard chew. It is 100% natural with no preservatives. From the beginning, we have tried numerous ways to utilize leftover Himalayan Dog Chews. After extensive research and hundreds of attempts later, we discovered that when Yaky Nuggets are microwaved, they puff up to about five times their original size. The result is a dog treat that is not too soft and not too hard, while maintaining the same cheesy flavor dogs love! Pieces much be microwaved for 1 minute to 1 minute 30 seconds. Please watch the microwave, as Himalayan puffs are made of cheese and do not pop like normal popcorn. The treats created from this ancient Himalayan recipe is made in the USA.