diff --git a/definitions/other.xml b/definitions/other.xml
index 4c02d0c..73b8e35 100644
--- a/definitions/other.xml
+++ b/definitions/other.xml
@@ -44,6 +44,13 @@
       <fraction n="0.95" ref="G4_POLYETHYLENE" />
    </material>
 
+   <!-- I haven't found a supplier with specifications, this is a guess -->
+   <material name="BoratedHDPE1pct" state="solid">
+      <D unit="g/cm3" value="0.96" />
+      <fraction n="0.01" ref="G4_B" />
+      <fraction n="0.99" ref="G4_POLYETHYLENE" />
+   </material>
+
    <!-- Scintillator with boron for neutron detection
    https://eljentechnology.com/products/plastic-scintillators/ej-254 -->
 
diff --git a/output/materials.xml b/output/materials.xml
index 55af3be..93496f8 100644
--- a/output/materials.xml
+++ b/output/materials.xml
@@ -3194,6 +3194,11 @@
       <fraction n="0.05" ref="G4_B"/>
       <fraction n="0.95" ref="G4_POLYETHYLENE"/>
    </material>
+   <material name="BoratedHDPE1pct" state="solid">
+      <D unit="g/cm3" value="0.96"/>
+      <fraction n="0.01" ref="G4_B"/>
+      <fraction n="0.99" ref="G4_POLYETHYLENE"/>
+   </material>
    <material name="EJ254-5pct" state="solid">
       <D unit="g/cm3" value="1.026"/>
       <fraction n="0.084647652" ref="G4_H"/>
diff --git a/output/rest.xml b/output/rest.xml
index 4a74a9c..c9adc7d 100644
--- a/output/rest.xml
+++ b/output/rest.xml
@@ -3522,6 +3522,11 @@
       <fraction n="0.05" ref="G4_B"/>
       <fraction n="0.95" ref="G4_POLYETHYLENE"/>
    </material>
+   <material name="BoratedHDPE1pct" state="solid">
+      <D unit="g/cm3" value="0.96"/>
+      <fraction n="0.01" ref="G4_B"/>
+      <fraction n="0.99" ref="G4_POLYETHYLENE"/>
+   </material>
    <material name="EJ254-5pct" state="solid">
       <D unit="g/cm3" value="1.026"/>
       <fraction n="0.084647652" ref="G4_H"/>