Kerr's distinctive purple-colored 37.5% phosphoric acid gel is designed for maximum etching efficiency. Its perfect viscosity allows the material to stay where it is placed, yet can be rinsed off easily. Kit: 3 x 3 g Gel Etchant Syringes, 30 Dispensing Tips Features and Benefits Perfect viscosity - stays where you place it No separation - delivery is always clean and easy Vibrant purple color - highly visible Rinses clean with minimum effort, easy to use