Trump said on Tuesday that he would impose a 50% tariff on copper. Though the remarks were light on specifics, his comments sent the metal to all-time highs.

Prices for the metal hit a record high after the president suggested a higher rate than many analysts were expecting.

President Trump’s proposed 50% tariff on copper imports would likely prove a boon for companies that mine copper in the U.S. So the question for investors is: Which stock should they buy to take advantage?