diff --git a/SimPEG/EM/FDEM/SrcFDEM.py b/SimPEG/EM/FDEM/SrcFDEM.py
index b55ad1db..327fca86 100644
--- a/SimPEG/EM/FDEM/SrcFDEM.py
+++ b/SimPEG/EM/FDEM/SrcFDEM.py
@@ -719,7 +719,7 @@ class PrimSecMappedSigma(BaseSrc):
     def _primaryFields(self, prob):
 
         # TODO: cache and check if prob.curModel has changed
-        return self.primaryProblem.fields(prob.curModel)
+        return self.primaryProblem.fields(prob.curModel.sigmaModel)
 
     def _primaryFieldsDeriv(self, prob, v, adjoint=False):
         if adjoint:
@@ -774,7 +774,7 @@ class PrimSecMappedSigma(BaseSrc):
 
 
     def s_e(self, prob):
-        sigmaPrimary = self.map2meshs * prob.curModel
+        sigmaPrimary = self.map2meshs * prob.curModel.sigmaModel
         return (prob.MeSigma -  prob.mesh.getEdgeInnerProduct(sigmaPrimary)) * self.ePrimary(prob)
 
 
@@ -783,8 +783,8 @@ class PrimSecMappedSigma(BaseSrc):
             raise NotImplementedError
             return prob.MeSigmaDeriv(self.ePrimary(prob)).T * v
 
-        sigmaPrimary = self.map2meshs * prob.curModel
-        sigmaPrimaryDeriv = self.map2meshs.deriv(prob.curModel)
+        sigmaPrimary = self.map2meshs * prob.curModel.sigmaModel
+        sigmaPrimaryDeriv = self.map2meshs.deriv(prob.curModel.sigmaModel)
         return (prob.MeSigmaDeriv(self.ePrimary(prob)) * v
                 - prob.mesh.getEdgeInnerProductDeriv(sigmaPrimary)(self.ePrimary(prob)) * sigmaPrimaryDeriv * v
                 + (prob.MeSigma -  prob.mesh.getEdgeInnerProduct(sigmaPrimary)) * self.ePrimaryDeriv(prob, v)
diff --git a/SimPEG/Maps.py b/SimPEG/Maps.py
index 4addfc1c..5391c86e 100644
--- a/SimPEG/Maps.py
+++ b/SimPEG/Maps.py
@@ -616,6 +616,37 @@ class Weighting(IdentityMap):
     def deriv(self, m):
         return self.P
 
+class Projection(IdentityMap):
+    """
+        A map to rearrange parameters
+
+    """
+
+
+    def __init__(self, indTo, indFrom, shape, mesh=None, **kwargs):
+
+        assert len(indTo) == len(indFrom)
+
+        self.P = sp.csr_matrix((np.ones(len(indTo)), (indTo, indFrom)), shape=shape)
+        self._shape = shape
+
+        super(Projection, self).__init__(mesh, **kwargs)
+
+    @property
+    def shape(self):
+        return self._shape
+
+    @property
+    def nP(self):
+        """Number of parameters in the model."""
+        return self.shape[1]
+
+    def _transform(self, m):
+        return self.P*m
+
+    def deriv(self, m):
+        return self.P
+
 
 class ComplexMap(IdentityMap):
     """ComplexMap