Non-toxic, smooth, dirt resistant. Soft flanges offer a better fit in the ear canal with a tighter seal and better attenuation for decreasing noise. Easy clean up with water allows for weeks and months of continuous use. Distinctive design allows one size to fit a wider range of ear canals. Size: 13.5mm (external), internal size fits earbuds with diameter from 3.5-7mm.* Replacement earbuds only, no headphones included.Different colors and sizes also available - visit our storefront for more!