Madewell Whisper Cotton Rib-Crewneck Tee in the color Optic White. Fabric is intentionally very light, airy, and breathable, and intentionally a little see-through. Right armpit has a very faint stain - I’m not even sure if it’s coming across on the pic, and I definitely don’t think it’s noticeable when worn, but just have to note. Make an offer & let me know if you have any questions.