COMPATIBLE WITH INVISALIGN, CUSTOM TRAYS, OR UNIVERSAL TRAY: (not included) Simply apply small drops along the upper and lower part of the tray and whiten to brilliant white teeth. 4-GEL SYRINGES (3cc each): 12-month shelf life. Each Gel provides 3- 4 whitening treatments. Compare to (Compared to Opalescence at-home gel 1.2cc). MADE IN USA. DENTIST APPROVED. SINCE 2003: This is the gel we have supplied dentists for 20 years. It works! Delivering bright dentist-white teeth. ENAMEL SAFE. NEAR-NEUTRAL PH. ZERO SENSITIVITY: Near-neutral pH for effective, comfortable tooth whitening at home for bright, white, confident teeth. 30-MINUTE TREATMENT: Apply gel to the upper / lower trays. Wear over teeth for up to 30 minutes. Use with Invisalign, aligners, and retainers (not included). 35% CARBAMIDE PEROXIDE TEETH WHITENING GEL FOR TRAYS: This is a higher-strength gel for fast tooth whitening results!.