Professional dental office-strength, 16 percent carbamide peroxide refill gel is great for those who already own bleaching trays from an at-home whitening system and need more gel. They may need to complete their dental-whitening project or do routine touchups. Our oversized, prefilled syringes (5 ml each) contain more whitening gel than most others and provide ten (10) whitening sessions each, offering 30 whitening applications. This gel is the exact formula professional dental offices use.