Allbirds, a San Francisco-based sneaker maker known for using sustainable material, raised $50 million in Series C funding. T. Rowe Price led and was joined by Fidelity and return backer Tiger Global.

Total funding has reached $75 million. Allbirds, which launched in 2016, will use the money to research sustainable materials and to execute an expansion strategy. A store is opening in London with shipping operations launching in the U.K. in 2019.

The company has stores in San Francisco, New York and Toronto.