However, Zwillinger has taken a different approach. Allbirds has worked hard to make most aspects of their footwear sustainable, including creating a foam called SweetFoam to be used on the bottom of sneakers made from a sugarcane waste stream. More often than not, this foam is typically derived from petroleum. Zwillinger has offered Amazon use of the sustainable innovation Allbirds came up with, as it will make an even bigger impact on the world than what his brand is doing. "If you replaced the oil-based products in your supply chain with this natural substitute (not just for one product, but all of them), we could jointly make a major dent in the fight against climate change. With the help of your immense scale, the cost of this material will come down for all users of this material, allowing for even broader adoption," he says. The patent to SweetFoam has been made public, which open-sources the technology to the rest of the world, including businesses like Amazon.