  We present a high precision Monte Carlo study of the spectrum of the Ising
gauge theory in three dimensions in the confining phase. Using state of the art
Monte Carlo techniques we are able to accurately determine up to three masses
in a single channel. We compare our results with the SU(2) spectrum and with
the prediction of the Isgur-Paton model. Our data strongly support the
conjecture that the glueball spectrum is described by some type of flux tube
model. We also compare the spectrum with some recent results for the
correlation length in the 3d spin Ising model. This analysis sheds light on
some nontrivial features of the duality transformation.
