REFILLS – Time for a refill? Our refills are a perfect alternative if you are already using a mouth tray. The teeth whitening gel works well with all mouth trays, regardless of whether they are from Beconfident or if you have received mouth trays from your dentist. For all of our complete teeth whitening kits, X1 Start Kit-X4 Pro Kit, we offer the corresponding tooth whitening gel as a refill so that you can easily maintain your beautiful, white smile.