HR® Lubricating Jelly, 2 ounce Tube, 1 Box of 12 Canes Specialty Pressure based sound frequency adjustment with Aluminum band assists in Pressure based sound frequency adjustment with tunable diaphragm Accepted by leading authorities as a simple and accurate method for discovering congenital color blindness and red green blindness each in two forms complete and incomplete * Includes four special plates for tests to determine the kind and degree of defect in color vision * Makes use of the peculiarity that in red green blindness blue and yellow appear remarkably bright compared with red and green * Color plates encased in specially designed album type books for ease of handling * Detailed instructions included HR lubricating jelly is water soluble so it can be cleaned away easily HR lubricating jelly is bacteriostatic – meaning lubricant inhibits spread of bacteria