Sometimes, the simplest invention can change millions of lives. That’s the goal of The Shoe That Grows, a sandal invented by inventor Kenton Lee that can adjust its size, allowing children in impoverished nations to grow up without having to go barefoot. The shoes, which come in catch-all Small and Large sizes, can grow 5 sizes and last at least 5 years.

According to The Shoe That Grows, “There are over 300 million children who do not have shoes. And countless more with shoes that do not fit.” Children without shoes are susceptible to injuries and parasites that infect humans through our feet. The problem with ordinary shoe donations is that they are soon outgrown, which is exactly the problem that these new shoes would fix.