Maintenance Kit 18% carbamide peroxide. Take Home Teeth Whitening Gel for patients with sensitivity issues and/or desire a short 30 minute wear time. Dual barrel syringe delivers perfectly blended carbamide peroxide and a water based activator for fast whitening results with virtually no sensitivity. Each 4ml dual barrel syringe is 5-6 complete treatments. Maintenance Kit Contains: 2 - 4ml automix syringes of Duet whitening gel, mixing tips, and patient instructions.