Many reusable breast pads use a synthetic material, such as polyurethane (PU) or thermoplastic polyurethane (TPU), to line or laminate the outer layer of the pad. These rubber-like materials offer breathability while also keeping wetness from soaking clothing or bras. The inner layer of fabric pads is usually an absorbent microfiber material, while the layer in contact with the skin is a soft cotton or bamboo fabric that won’t irritate nipples.