Jackman Back Nep Umps Shorts Sumikuro / Ink BlackJackman Back Nep Umps Shorts in Sumikuro Ink Black. These AMPUS shorts are made from a fabric material that is spun into nep yarn in Japan and woven from organic cotton. PRODUCT FEATURES It requires high skill to create a natural, rustic surface and control the varying strengths of the neps. Usually, the surface is mercerized to create a beautiful finish, but in order to bring out the roughness of organic cotton, these shorts are not mercerized but