Here's what other sites are saying:
2NDS . Kenyon's silkweight long underwear top is great for running, cycling or any highly aerobic outdoor sport. Durable Silkyester lightweight polyester resists odor, stains and dirt. Long sleeves Care: Machine wash/dry Made in Honduras, components USA. May be 100% polyester or at least 50% polyester, remainder other fabric, may not specify.
- Sierra Trading Post