A nut is a type of fastener with a threaded hole. Nuts are almost always used in conjunction with a mating bolt to fasten multiple parts together. The two partners are kept together by a combination of their threads friction with slight elastic deformation, a slight stretching of the bolt, and compression of the parts to be held together. A tube tubular section, tubing, or hollow cylinder usually but not necessarily of circular crosssection, used mainly to convey substances which can flow liquids and gases fluids, slurries, powders and masses of small solids. Plastic tubing is widely used for its light weight, chemical resistant, noncorrosive properties, and ease of making connections. A tube may also reference a florescent light bulb or a housing of lamps or LEDs. Specifications. Height 0.85 in. . Width 4 in. . Length 2.35 in.