Opalescence PF bleach syringes are easy to use and have longlasting effects. Opalescence PF was the first ADA accepted syringe delivered tooth whitening sustem that showed significant whitening in days. The active ingredient, carbamide peroxide is both safe and effective at removing most stains. Available in two strengths: 15% for most stains, 20% for stubborn discolorations. Each kit contains 4 prefilled syringes. You must already have custom made bleach trays to use these syringes. If you do not have custom trays, take a look at the TresWhite system by Opalescence. Opalescence 15% 4 Pack $26.00 Opalescence PF 15% 8 Pack $45.00 Opalescence PF 20% 4 Pack $32.00 Opalescence PF 20% 8 Pack $51.00