Conforms to EN 352-2 H = 29, M = 25, L =23, SNR = 28. 1028457 Patented "no-roll" design is easy to handle and fit. Contoured shape comfortably matches contours of the ear canal. Smooth, non-irritating skin provides all-day comfort, easy to clean for long-term use. Built-in insertion stem makes insertion quick and easy.