"XJG conduit expansion couplings for EMT and rigid/IMC are used with EMT, rigid metal conduit and IMC to couple together two sections of conduit subject to longitudinal movement. They are installed indoors or outdoors in long conduit runs to permit linear movement caused by thermal expansion and contraction to prevent damage to conduit supports and electrical systems in building or bridges. XJGs for rigid/IMC and EMT are also available with a hot dip galvanized finish (standard for trade sizes 1-1/4"" and above) for added corrosion protection against harsh environmental factors.