  In a recent paper Coldea et al (2010 Science {\bf 327} 177) report
observation of the weak confinement of kinks in the Ising spin chain
ferromagnet CoNb2O6 at low temperatures. To interpret the entire spectra of
magnetic excitations measured via neutron scattering, they introduce a
phenomenological model, which takes into account only the two-kink
configurations of the spin chain. We present the exact solution of this model.
The explicit expressions for the two-kink bound-state energy spectra and for
the relative intensities of neutron scattering on these magnetic modes are
obtained in terms of the Bessel function.
