diff --git a/nifty5/operators/domain_distributor.py b/nifty5/operators/domain_distributor.py
index a555196b1531fede651aa71dc66b70b594397124..aa5b39474e4bab73307077ce561b2e244b23fcc2 100644
--- a/nifty5/operators/domain_distributor.py
+++ b/nifty5/operators/domain_distributor.py
@@ -6,9 +6,9 @@ from ..domain_tuple import DomainTuple
 from .linear_operator import LinearOperator
 
 
+# MR FIXME: this needs to be rewritten in a generic fashion
 class DomainDistributor(LinearOperator):
     def __init__(self, target, axis):
-        # TODO Replace this by a DiagonalOperator
         if dobj.ntask > 1:
             raise NotImplementedError('UpProj class does not support MPI.')
         assert len(target) == 2
diff --git a/nifty5/operators/multi_adaptor.py b/nifty5/operators/multi_adaptor.py
index b54cc4cd1c23068dafe1bd9ebba02fbed5c22eee..6286804230b1b5f31871c7c581332cb2a0872b0f 100644
--- a/nifty5/operators/multi_adaptor.py
+++ b/nifty5/operators/multi_adaptor.py
@@ -17,12 +17,10 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from ..multi.multi_domain import MultiDomain
-from ..multi.multi_field import MultiField
-from .linear_operator import LinearOperator
 
 
-class MultiAdaptor(LinearOperator):
-    """Transforms a Field into a MultiField and vise versa when
+def MultiAdaptor(target):
+    """Transforms a Field into a MultiField and vice versa when
     using adjoint_times.
 
     Parameters
@@ -30,30 +28,8 @@ class MultiAdaptor(LinearOperator):
     target: MultiDomain
         MultiDomain with only one entry (key).
     """
-
-    def __init__(self, target):
-        super(MultiAdaptor, self).__init__()
-        if not isinstance(target, MultiDomain) or len(target) > 1:
-            raise TypeError
-        self._target = target
-        self._domain = list(target.values())[0]
-
-    @property
-    def domain(self):
-        return self._domain
-
-    @property
-    def target(self):
-        return self._target
-
-    @property
-    def capability(self):
-        return self.TIMES | self.ADJOINT_TIMES
-
-    def apply(self, x, mode):
-        self._check_input(x, mode)
-        key = list(self.target.keys())[0]
-        if mode == self.TIMES:
-            return MultiField({key: x})
-        else:
-            return x[key]
+    if not isinstance(target, MultiDomain) or len(target) > 1:
+        raise TypeError
+    return SelectionOperator(target,target.keys()[0]).adjoint
+    self._target = target
+    self._domain = list(target.values())[0]
diff --git a/nifty5/operators/symmetrizing_operator.py b/nifty5/operators/symmetrizing_operator.py
index 49a4c4df37463f0b56484d8ac27ee720fe572ade..44d2aba7fbdbc4103e81bf5797c5430f88c04f30 100644
--- a/nifty5/operators/symmetrizing_operator.py
+++ b/nifty5/operators/symmetrizing_operator.py
@@ -4,6 +4,7 @@ from .endomorphic_operator import EndomorphicOperator
 from .. import dobj
 
 
+# MR FIXME: we should make sure that the domain is a harmonic RGSpace, correct?
 class SymmetrizingOperator(EndomorphicOperator):
     def __init__(self, domain):
         self._domain = DomainTuple.make(domain)