I know the material is satin but if I didn’t know and someone told me it was silk, I would believe it. The satin material is very high quality and unlike any other satin bonnet I’ve purchased. I love how it’s just as silky on the inside as it is on the outside. A lot of times, bonnets will have a silky exterior but a rough interior which never made sense to me. All in all, this thing is super comfortable on my head and I haven’t even needed to use the jaw string to tighten or loosen because it fits perfectly.