The set contains 4 flexible rings ranging in size from 0.4 to 0.75 in. unstretched. The rings are easy to place and remove, even with slippery hands, because each tab features a thick border, allowing the rings to be adjusted with ease. The set is made of non-phthalate TPR. Ring sizes: small, 0.4 in. inside diameter (ID), stretches up to 2 in.; medium, 0.5 ID, stretches up to 2.5 in.; large, 0.6 in. ID, stretches up to 3 in.; extra large, 0.9 in. ID, stretches up to 3.5 in.