A magnetic tunnel junction cell having a free layer, a ferromagnetic pinned layer, and a barrier layer therebetween. The amide compound and the polyhydric alcohol in the ink composition decrease the mobility of coloring agents and increase the adhesion to media, thereby minimizing the bleeding between colors of printed images, and improving the water fastness and dry and wet rub fastness to provide good color fastness on papers. The end surface of the one light conducting element is spherically concave and the end surface of the other light conducting element is formed spherically convex with the same radius of curvature. Each paperboard panel may define an opening to seat a plastic component.