This sounding dialater kit has 8 pieces. Each dialater is  8 inches (20.3 cm) long. The sounds are straight which make for easy insertion. They are made out of chrome-plated brass. Also each end is a little larger on one end than on the other, so you actually get a total of 16 different sizes. Sizes go from 1/8 inch (.32 cm) to the largest which is  9/16 inch (1.43 cm) wide. The kit comes in a zippered storage case. Note: we recommend Surgilube for lubrication.