The Memory Foam Step-In Harness is a direct replacement of our Trekking Harness, which was wildly popular among tiny dog breeds because it would even fit a small Chihuahua. If you have a tiny furry child, chances are you know the struggle of finding a good harness that would fit. Frankly, there aren't many harnesses out on the market that are tailored to tiny dogs, let alone small harnesses with functionalities. This was why we created our Memory Foam Step-In Harness. Memory Foam * Adds comfort * Helps to reduce impact * Hypoallergenic - helps to reduce allergen from building up * Conforms to the curves of your dog's body * Isolates and absorbs motion * Durable and long lasting Extra Small Sizing Options Fits even the tiniest of the small dog breeds such as Chihuahuas, Yorkies, and Pomeranians.