diff -r 402d717bb5c0 -r dab30b331f49 src/direct_product.rs
--- a/src/direct_product.rs	Mon Sep 01 20:55:34 2025 -0500
+++ b/src/direct_product.rs	Mon Sep 01 23:03:27 2025 -0500
@@ -6,7 +6,9 @@
 */
 
 use crate::euclidean::Euclidean;
-use crate::instance::{Decomposition, DecompositionMut, Instance, InstanceMut, MyCow, Ownable};
+use crate::instance::{
+    Decomposition, DecompositionMut, EitherDecomp, Instance, InstanceMut, MyCow, Ownable,
+};
 use crate::linops::{VectorSpace, AXPY};
 use crate::loc::Loc;
 use crate::mapping::Space;
@@ -279,6 +281,14 @@
     fn clone_owned(&self) -> Self::OwnedVariant {
         Pair(self.0.clone_owned(), self.1.clone_owned())
     }
+
+    fn owned_cow<'b>(self) -> MyCow<'b, Self::OwnedVariant> {
+        EitherDecomp::Owned(self.into_owned())
+    }
+
+    fn ref_owned_cow<'b>(&self) -> MyCow<'b, Self::OwnedVariant> {
+        EitherDecomp::Owned(self.into_owned())
+    }
 }
 
 /// We only support 'closed' `Euclidean` `Pair`s, as more general ones cause
@@ -439,19 +449,6 @@
         self.0
             .eval_ref_decompose(|a| self.1.eval_ref_decompose(|b| f(Pair(a, b))))
     }
-
-    #[inline]
-    fn cow<'b>(self) -> MyCow<'b, Pair<A, B>>
-    where
-        Self: 'b,
-    {
-        MyCow::Owned(Pair(self.0.own(), self.1.own()))
-    }
-
-    #[inline]
-    fn own(self) -> Pair<A, B> {
-        Pair(self.0.own(), self.1.own())
-    }
 }
 
 impl<'a, A, B, U, V, D, Q> Instance<Pair<A, B>, PairDecomposition<D, Q>> for &'a Pair<U, V>
@@ -490,20 +487,6 @@
         self.0
             .eval_ref_decompose(|a| self.1.eval_ref_decompose(|b| f(Pair(a, b))))
     }
-
-    #[inline]
-    fn cow<'b>(self) -> MyCow<'b, Pair<A, B>>
-    where
-        Self: 'b,
-    {
-        MyCow::Owned(self.own())
-    }
-
-    #[inline]
-    fn own(self) -> Pair<A, B> {
-        let Pair(ref u, ref v) = self;
-        Pair(u.own(), v.own())
-    }
 }
 
 impl<A, B, D, Q> DecompositionMut<Pair<A, B>> for PairDecomposition<D, Q>