It is a gray hair cover product.

I was really worried about the gray hairs being too noticeable on my bangs and the sides, and this product caught my eye.

It's great for quick outings since you just swipe it on like mascara. I use it occasionally when I'm in a hurry because dyeing your hair too often isn't good. The downside is that if you don't control the amount properly, your hair becomes stiff and can look greasy. You really have to use it carefully.