Lightweight undershirt made of 90% polyester for a comfortable fit. - Color: Blue - Material: 90% polyester, 10% polyurethane - Brand: TOPVALU Thank you for viewing. The armpits are mesh, so I think it's breathable. I'm selling this because I outgrew it without ever wearing it. Although it's unused, it has been stored in a drawer for several years, so please refrain from purchasing if you are concerned. Thank you.