6% hydrogen-peroxide pen. Pair the Colgate^® Optic White^® Professional Refill Pen with the Colgate^® Optic White^® Professional LED Teeth Whitening Device (sold separately) for whitening made simple with our best at-home whitening technology. Patients can achieve dramatically whiter teeth in just 5 days when used as directed. Professional-strength serum that is enamel safe. Our whitening formula is easy to apply, designed for no tooth sensitivity, no gum irritation, and no mess. Dentist exclusive.