The new Tree Flyer performance running shoe from Allbirds is said to have a carbon footprint of 9.92 kg CO2e, all of which is offset to zero.

Created at what Allbirds calls the intersection of innovative technology, renewable natural materials, and instantaneous material circularity, the Tree Flyer is said to have more bounce, more propulsion, and a 70% rebound rate that helps give runners more energy with every step thanks to SwiftFoam technology.

While midsoles are usually made from petroleum and are 100% synthetic, SwiftFoam leverages natural castor beans, a renewable natural resource that has a 20% lower carbon footprint than a petroleum-based alternative.

What’s more, nearly 100% of the excess waste created while making the midsole is instantaneously recycled to craft the external heel counter.

Allbirds says the Tree Flyer’s bouncy, airy SwiftFoam midsoles are approximately 30% more responsive, 25% lighter and require less energy to manufacture than its existing SweetFoam technology, with the shoe weighing in at 269g, the lightest running shoe made exclusively by Allbirds.

The shoe also features a knit structure, made from Allbirds’ signature eucalyptus-based Tree fibre to help secure the foot for a performance fit while providing breathability and increased durability, and a new zonal traction pattern to provide ample grip while maintaining flexibility.

“The Tree Flyer is a true technical and environmental achievement, and demonstrates that the right mix of expertise, diligence, and vision can lead to groundbreaking innovations,” says Tim Brown, co-CEO and co-founder of Allbirds. “Getting this mix right, without a runner’s performance or the planet left behind, represents one of the greatest challenges and opportunities for our team.”

Last month, Allbirds and German sportswear giant Adidas released a new iteration of their Futurecraft.Footprint shoe to demonstrate that low-carbon running shoes can be delivered at scale.