The 16% / 22% Carbamide Peroxide refill gel is great for those who already have bleaching trays. Use the dental office strength gel to complete your dental whitening project or to do routine touch-ups. Our 3 oversized pre-filled syringes (5ml each) contain more whitening gel than most others and provides 30-40 whitening applications in total. This gel is the exact formula used by professional dental offices.