According to The NDP Group, battery pack sales doubled in the US during the estimated two weeks that followed the debut of Pokemon GO. That’s a lot of battery powerbanks needed to consistently play Pokemon GO! It reports seeing a year over year 101% growth. That’s 1.2 million powerbank units being sold between July 10 and 23 ever since July 6, the game’s official release.

Pokémon Go really seems to be the only explanation here. NPD notes that while battery pack sales have generally been increasing from 2015, sales were only up 4 percent in the weeks prior to the game’s release. So Pokémon Go very much seems to be what triggered it. The custom Pokéball batteries that popped up may have helped, too.

The question now is how battery packs — and Pokémon Go — will fair in the weeks ahead. It’s not outrageous to assume that the Pokémon Go phenomenon will fade with time, and battery pack sales are likely to go down along with it. How soon will that happen? Niantic still has most of the world to roll the game out to, but it’ll want to do that without annoying existing players too much.