Like all Woolpower LITE items, the T-Shirts are intended for wear as base layers in warm weather, or in situations where warm weather can potentially turn cool or cold.The Woolpower LITE is a pleasure to wear in any conditions, even truly hot weather when most people would think of cotton or some light synthetic. If you are going someplace where warm and pleasant weather can potentially turn cold and nasty, in my opinion it is not worth taking the chance. But even if a change from warm or hot to nasty is not a concern, this LITE merino wool will outperform other materials.Unlike the long-established cold-weather Woolpower, the Summerweight LITE items are a typical flat-knit (1x1 rib knit).These come in BLACK with contrasting waistband and stripe.Composition: 80% Merino Wool; 20% Polyamide.