diff --git a/measurements.py b/measurements.py
index e2ef629..a13e011 100644
--- a/measurements.py
+++ b/measurements.py
@@ -15,7 +15,8 @@ class Template(metaclass=PoolMeta):
     frequency_uom = fields.Many2One('product.uom', "Frequency UOM",
                                       domain=[('category', '=', Id('optical_equipment', 'uom_cat_frequency'))])
     wet = fields.Float("Wet")
-    wet_uom = fields.Many2One('product.uom', "Wet UOM")
+    wet_uom = fields.Many2One('product.uom', "Wet UOM",
+                                      domain=[('category', '=', Id('optical_equipment', 'uom_cat_relative_humedity'))])
     voltageAC = fields.Float("Voltage AC")
     voltageAC_uom = fields.Many2One('product.uom', "Voltage AC UOM",
                                       domain=[('category', '=', Id('optical_equipment', 'uom_cat_electrical_tension'))])
diff --git a/uom.xml b/uom.xml
index 21786b1..156c155 100644
--- a/uom.xml
+++ b/uom.xml
@@ -69,5 +69,18 @@ this repository contains the full copyright notices and license terms. -->
             <field name="rounding" eval="1."/>
             <field name="digits" eval="0"/>
 	</record>
+	<record model="product.uom.category" id="uom_cat_relative_humedity">
+            <field name="name">Relative Humedity</field>
+        </record>
+	<record model="product.uom" id="uom_relative_humedity">
+            <field name="name">Relative Humedity</field>
+            <field name="symbol">%HR</field>
+            <field name="category" ref="uom_cat_relative_humedity"/>
+            <field name="rate" eval="1."/>
+            <field name="factor" eval="1."/>
+            <field name="rounding" eval="1."/>
+            <field name="digits" eval="0"/>
+	</record>
+
     </data>
 </tryton>