Single Black Trunks. Calvin Klein Underwear, curated by Reiss, is a collection of lingerie designed to elevate the underwear drawer and work perfectly beneath your existing Reiss garments. Feel comfortable from the first layer. These best-selling black trunks are crafted from a microfibre jersey for everyday comfort. They’re cut to a low rise on the waist and feature the brand’s signature monogram waistband in a tonal black shade. Microfibre jersey Low rise Signature monogram waistband