Objects supported by electron degeneracy pressure
span a broad range of masses.  The low-mass end of this
range, which is near the mass of Saturn, is set by the
transition from pressure exerted by atoms to pressure
exerted by degenerate electrons.  The high end of this range,
which is 1.4 solar masses, is set by the gravitational
instability that arises when the degenerate electrons have
kinetic energies equal to the electron rest-mass energy.
These limits are given by several fundamental constants
of physics.  Despite the neutron stars being supported
by neutron and proton degeneracy pressure rather than
electron degeneracy pressure, they have an upper mass
similar to that of the degenerate dwarf.