diff --git a/properties/P000172.md b/properties/P000172.md
index 53dba5c78..545886d9a 100644
--- a/properties/P000172.md
+++ b/properties/P000172.md
@@ -19,3 +19,6 @@ Compare with {P80}.
 
 - This property is hereditary.
 - $X$ satisfies this property iff its Kolmogorov quotient $\text{Kol}(X)$ does.
+- If each point has a neighborhood with the property, $X$ also has the property.
+- This property is not preserved by products
+(Example: {S78|P172}).
diff --git a/theorems/T000839.md b/theorems/T000839.md
new file mode 100644
index 000000000..e7b94975e
--- /dev/null
+++ b/theorems/T000839.md
@@ -0,0 +1,10 @@
+---
+uid: T000839
+if:
+  P000120: true
+then:
+  P000172: true
+---
+
+Each point has a neighborhood that is {P133} and hence {P172}
+[(Explore)](https://topology.pi-base.org/spaces?q=LOTS%2B%7ERadial).