The Meissner effect says that a superconducting metal will try to expel magnetic field lines from its interior.
If the quark–antiquark pair are immersed in a dual superconductor, then the electric field lines get compressed to a flux tube.
The potential energy of colored objects becomes infinite in the limit of large separation, all else being equal, though in reality, when it becomes large enough to form a new quark-anti-quark pair from the vacuum, these split the flux tube and bind to the original anti-quark and quark.
The MIT bag model boundary conditions for gluon fields are those of the dual color superconductor.
The dual superconductor model is motivated by several observations in calculations using lattice gauge theory.