  The U-CAS is a spinning magnetized top that is levitated in a static magnetic
field. The field is produced by a permanent magnet base, positioned below the
hovering top. In this paper we derive upper and lower bounds for h - the
maximum hovering height of this top. We show that the bounds are of the form
a*L where a is a dimensionless number ranging from about 1 to 12, depending on
the constraints on the shape of the base and on stability considerations, and L
is a characteristic length for the problem. For modern permanent magnets we
find that L=~1[meter], thus limiting h to about few meters.
