The Smileactives Wintergreen variant Teeth Whitening Pen is a portable, 0.11 oz, brush-on, hydrogen peroxide-based whitening treatment designed for on-the-go use. It provides clinical-grade results in as little as 7 days (or 2 days in some studies) without trays or strips. The formula dries quickly, freshens breath with a minty, berry flavor, and is safe for enamel.