Bell Demonstration Model, All The Components Of Electric Bell Are Mounted On A Large Panel. Allwiring Is Visible And Parts Are Of Large Size. Operates On 4-6 Volts Dc, Mounted On A Large Panel, All Parts Easily Visible, Rigid Constructions
Replacement Sand, set is a refill of the sand included with the Tectonics model. Set includes one pound each of beige, black, blue, orange and yellow sand