From COLGATE
Enjoy quick, easy and no mess precision application of the serum with the Colgate Optic White O2 Teeth Whitening Pen. Within seconds, the 0.1% Hydrogen Peroxide as whitening active ingredient serum forms a smudge-proof, concentrated layer of active oxygen which absorbs into teeth, starting the whitening process. Wake up with a smile that you will love to stare at.