Use this versatile looping track to demonstrate topics including acceleration, critical velocity, centripetal force, and Conservation of Energy.  Size and price perfect for use by students in classroom laboratories.  One 3/4" steel ball and one 5/8" steel ball included.  3/4" wooden and glass balls available separately.  Dimensions:  Base: 16", Loop diameter: 8", Overall Height: 20".  Available in sets of 8 only.  Shipped directly from manufacturer.