Polo Ralph Lauren NCKBP5 Classic Fit Cotton Knit Boxers - 5 Pack (Polo Black (M) Polo Ralph Lauren Classic Fit Cotton Knit Boxers - 5 Pack (NCKBP5). The Polo Ralph Lauren Classic Fit Cotton Knit Boxers - 5 Pack NCKBP5 features the iconic Polo player sewn into soft, breathable knit at lower front left. Classic fitting boxer wicks moisture away from the skin, has button fly, and stays in place with logo waistband. Polo Ralph Lauren's Classic Fit Cotton Knit Boxers - 5 Pack is made of cotton/polyester/spandex.