The company that boycotts logos and makes 'the world's most comfortable shoes' just raised $17.5 million to open stores

Allbirds is taking flight.

The company known for its super-soft sneakers - made out of a proprietary Merino wool blend and dubbed the most comfortable in the world - announced a $17.5 million Series B funding round on Tuesday, led by investment firm Tiger Global.

That brings the total raised by the company to $27.5 million since its founding in 2015.

The sneakers caught on as the shoe du jour in Silicon Valley in 2016, and fans praised their comfort and accessible price.

The wool blend is soft to the touch. Allbirds encourages customers to wear the shoes without socks and throw them in the washing machine. The company currently sells two wool shoes: a version with laces, called the runner, and a slip-on, known as the lounger, released earlier this year.

Allbirds cofounder Tim Brown told Business Insider the company will use the cash to open new physical store locations. Allbirds currently has one store under the company's headquarters in San Francisco, and another is opening this month in another undisclosed city in the US. Brown says others are planned.

"Retail is a big part of our future," Brown said. "We think there's a really great opportunity to rethink retail and rethink how shoes are tried on, and just think through every step of that process."

Allbirds currently only ships shoes to the US and New Zealand, but Brown said the cash will also be used to help the company offer its products online in more countries around the world.

Brown says the company hasn't lost sight of its original mission, which is something he calls "natural material innovation": creating "better" shoes from sustainable materials, like wool, that aren't traditionally used in footwear and are more environmentally friendly to boot.

The funding will help that research into new materials, according to Brown, and will eventually help solve other problems in footwear.

"We think there's a pipeline of other materials, many of which we've already been working on, and this funding will really allow us to double down on that innovation that will really fuel the growth of the business going forward," Brown said.

In the future, he said, that "natural material innovation" may extend to other products, but the focus is just on shoes for now.

"The idea that underpins Allbirds is larger than just shoes, but at the moment we're laser-focused on it," Brown said.

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