Index: Riskeer/Common/src/Riskeer.Common.Forms/PropertyClasses/WaterLevelCalculationsForUserDefinedTargetProbabilityProperties.cs
===================================================================
diff -u -r5970157264549d811f0bfa9d195d9afb4331511e -re9a7cd0f9675981fcf2d27af141f04da4a17f55d
--- Riskeer/Common/src/Riskeer.Common.Forms/PropertyClasses/WaterLevelCalculationsForUserDefinedTargetProbabilityProperties.cs	(.../WaterLevelCalculationsForUserDefinedTargetProbabilityProperties.cs)	(revision 5970157264549d811f0bfa9d195d9afb4331511e)
+++ Riskeer/Common/src/Riskeer.Common.Forms/PropertyClasses/WaterLevelCalculationsForUserDefinedTargetProbabilityProperties.cs	(.../WaterLevelCalculationsForUserDefinedTargetProbabilityProperties.cs)	(revision e9a7cd0f9675981fcf2d27af141f04da4a17f55d)
@@ -20,6 +20,7 @@
 // All rights reserved.
 
 using System;
+using System.ComponentModel;
 using Core.Common.Util.Attributes;
 using Core.Gui.Attributes;
 using Riskeer.Common.Data.Hydraulics;
@@ -37,8 +38,6 @@
         private const int targetProbabilityPropertyIndex = 1;
         private const int calculationsPropertyIndex = 2;
 
-        private static readonly NoProbabilityValueDoubleConverter noProbabilityValueDoubleConverter = new NoProbabilityValueDoubleConverter();
-
         private readonly HydraulicBoundaryLocationCalculationsForTargetProbability calculationsForTargetProbability;
 
         /// <summary>
@@ -62,15 +61,20 @@
         }
 
         [PropertyOrder(targetProbabilityPropertyIndex)]
+        [TypeConverter(typeof(NoProbabilityValueDoubleConverter))]
         [ResourcesCategory(typeof(Resources), nameof(Resources.Categories_General))]
         [ResourcesDisplayName(typeof(Resources), nameof(Resources.TargetProbability_DisplayName))]
         [ResourcesDescription(typeof(Resources), nameof(Resources.TargetProbability_WaterLevels_Description))]
-        public string TargetProbability
+        public double TargetProbability
         {
             get
             {
-                return noProbabilityValueDoubleConverter.ConvertToString(calculationsForTargetProbability.TargetProbability);
+                return calculationsForTargetProbability.TargetProbability;
             }
+            set
+            {
+                calculationsForTargetProbability.TargetProbability = value;
+            }
         }
     }
 }
\ No newline at end of file
Index: Riskeer/Common/src/Riskeer.Common.Forms/PropertyClasses/WaveHeightCalculationsForUserDefinedTargetProbabilityProperties.cs
===================================================================
diff -u -r628f2f0fb1146e8b4bce994f9d81971adf6791b7 -re9a7cd0f9675981fcf2d27af141f04da4a17f55d
--- Riskeer/Common/src/Riskeer.Common.Forms/PropertyClasses/WaveHeightCalculationsForUserDefinedTargetProbabilityProperties.cs	(.../WaveHeightCalculationsForUserDefinedTargetProbabilityProperties.cs)	(revision 628f2f0fb1146e8b4bce994f9d81971adf6791b7)
+++ Riskeer/Common/src/Riskeer.Common.Forms/PropertyClasses/WaveHeightCalculationsForUserDefinedTargetProbabilityProperties.cs	(.../WaveHeightCalculationsForUserDefinedTargetProbabilityProperties.cs)	(revision e9a7cd0f9675981fcf2d27af141f04da4a17f55d)
@@ -20,6 +20,7 @@
 // All rights reserved.
 
 using System;
+using System.ComponentModel;
 using Core.Common.Util.Attributes;
 using Core.Gui.Attributes;
 using Riskeer.Common.Data.Hydraulics;
@@ -37,8 +38,6 @@
         private const int targetProbabilityPropertyIndex = 1;
         private const int calculationsPropertyIndex = 2;
 
-        private static readonly NoProbabilityValueDoubleConverter noProbabilityValueDoubleConverter = new NoProbabilityValueDoubleConverter();
-
         private readonly HydraulicBoundaryLocationCalculationsForTargetProbability calculationsForTargetProbability;
 
         /// <summary>
@@ -62,15 +61,20 @@
         }
 
         [PropertyOrder(targetProbabilityPropertyIndex)]
+        [TypeConverter(typeof(NoProbabilityValueDoubleConverter))]
         [ResourcesCategory(typeof(Resources), nameof(Resources.Categories_General))]
         [ResourcesDisplayName(typeof(Resources), nameof(Resources.TargetProbability_DisplayName))]
         [ResourcesDescription(typeof(Resources), nameof(Resources.TargetProbability_WaveHeights_Description))]
-        public string TargetProbability
+        public double TargetProbability
         {
             get
             {
-                return noProbabilityValueDoubleConverter.ConvertToString(calculationsForTargetProbability.TargetProbability);
+                return calculationsForTargetProbability.TargetProbability;
             }
+            set
+            {
+                calculationsForTargetProbability.TargetProbability = value;
+            }
         }
     }
 }
\ No newline at end of file