  It is well known$^{1,2}$ that in one-dimensional disordered system all states
of electrons (or any other exitations) are localized. In this letter it is
shown that delocalized states exist in a rather broad class of of simple
models, but a set of delocalized states is not too great, and it does not
contradict this theorem in more precize form$^{2,3}$. These systems can be
considered as filters in energy for electrons.
