A conventional horizontal axis portion is divided into two to have a triaxial structure including a vertical axis portion. There are enclosed at least two substances having different states andor masses, whereof at least one visible interface physically represents sight markers, when the device is positioned in the peripheral visual field of one eye or both eyes of the user. The buyer computers, seller computers and server computer are interconnected as a computer network. The opposing directions can include substantially all directions normal to an interior surface defining a fluid conduit over a selected length of the fluid conduit.