3 Matching bras are made from bamboo viscose which is very comfortable & breathable. These would be comfortable to wear during the day or to sleep in. Didn't read reviews that this brand runs small, so though they're a Large they would fit a M (S?) better. Only worn & washed a few times. Photos are a bit shadowed, but these have no discoloration or staining. Halter Bra fits similarly & has a stretchy back.