This item is used for comparing the thermal conductivities of aluminum, brass, steel, nickel, and copper. The five radial spokes are attached to a brass hub. Each rod is marked with the metal name on the hub. There are notches in each rod to hold a wax pellet. The unit comes assembled and with a supply of wax. Dimensions: 14" x 7" x 1". Unit comes assembled, with a supply of wax and an activity guide.