3ml 35% carbamide peroxide teeth whitening gel good effect to teeth whitening High Viscosity Gel is important because it allows the gel to stick to your teeth. This is essential to the whitening process. If a gel is not highly viscous, the whitening gel will leak out of the bottom of the bleaching tray.That slows the whitening process and creates unneeded sensitivities. As well, saliva can dilute a low-viscosity gel, rendering it non-effective.Our gels are all high viscosity - so the gels remain on the teeth throughout any bleaching session pls. contact us for more information