Why not start with a signature classic with the Calvin Klein Underwear Micro Stretch Boxer Brief 3-Pack. Elasticized waistline. Anatomical design for ultimate comfort. 88% polyester, 12% elastane. Machine wash tumble dry. Why not start with a signature classic with the Calvin Klein Underwear Micro Stretch Boxer Brief 3-Pack. Elasticized waistline. Anatomical design for ultimate comfort. 88% polyester, 12% elastane. Machine wash tumble dry.