There is no way this is 100% wool. I own all kinds of pure wool and pure cashmere and the only way for this tank to have this kind of firm/elastic stretch is for it to have some spandex or other poly or nylon woven into it. You can feel this just by touching the fabric without even testing for the synthetic elastic stretch. It's a nice enough camisole, but dishonestly described and priced as "100% wool." Yes, wool is warm, but part of the insulation factor in this tank is the synthetic fabric added to the wool.