Switch the thickness remap to centimeters and set the low thickness threshold to 0.5 cm

Assets/ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/Lit.hlsl

 #define LTC_LUT_OFFSET (0.5 * rcp(LTC_LUT_SIZE))
 
 // SSS parameters
-#define SSS_N_PROFILES      8
-#define SSS_UNIT_CONVERSION (1.0 / 300.0)                  // From 1/3 centimeters to meters
-#define SSS_LOW_THICKNESS   0.002                          // 2 mm
+#define SSS_N_PROFILES        8
+#define SSS_UNIT_CONVERSION   (1.0 / 300.0)                // From 1/3 centimeters to meters
+#define SSS_LOW_THICKNESS     0.005                        // 0.5 cm
+#define CENTIMETERS_TO_METERS (1.0 / 100.0)
 
 uint   _EnableSSS;                                         // Globally toggles subsurface scattering on/off
 uint   _TransmissionFlags;                                 // 1 bit/profile; 0 = inf. thick, 1 = supports transmission
     // Thickness and SSS radius are decoupled for artists.
     // In theory, we should modify the thickness by the inverse of the radius scale of the profile.
     // thickness /= radiusScale;
-    thickness /= SSS_UNIT_CONVERSION;
+    thickness /= CENTIMETERS_TO_METERS;
 
     float t2 = thickness * thickness;
 
     bsdfData.subsurfaceProfile = subsurfaceProfile;
     // Make the Std. Dev. of 1 correspond to the effective radius of 1 cm (three-sigma rule).
     bsdfData.subsurfaceRadius = SSS_UNIT_CONVERSION * subsurfaceRadius + 0.0001;
-    bsdfData.thickness = SSS_UNIT_CONVERSION * (_ThicknessRemaps[subsurfaceProfile][0] +
-                                                _ThicknessRemaps[subsurfaceProfile][1] * thickness);
+    bsdfData.thickness = CENTIMETERS_TO_METERS * (_ThicknessRemaps[subsurfaceProfile][0] +
+                                                  _ThicknessRemaps[subsurfaceProfile][1] * thickness);
 
     bsdfData.enableTransmission = IsBitSet(_TransmissionFlags, subsurfaceProfile);
     if (bsdfData.enableTransmission)

Assets/ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/SubsurfaceScatteringProfile.cs

         private class Styles
         {
             public readonly GUIContent   sssProfilePreview0        = new GUIContent("Profile Preview");
-            public readonly GUIContent   sssProfilePreview1        = new GUIContent("Shows the fraction of light scattered from the source as radius increases to 1.");
+            public readonly GUIContent   sssProfilePreview1        = new GUIContent("Shows the fraction of light scattered from the source as the radius increases to 1.");
-            public readonly GUIContent   sssTransmittancePreview1  = new GUIContent("Shows the fraction of light passing through the object as thickness increases to 1.");
+            public readonly GUIContent   sssTransmittancePreview1  = new GUIContent("Shows the fraction of light passing through the object for thickness values from the remap.");
+            public readonly GUIContent   sssTransmittancePreview2  = new GUIContent("Can be thought of as a cross section of a slab of material illuminated by a white light from the left.");
             public readonly GUIContent   sssProfileStdDev1         = new GUIContent("Standard Deviation #1", "Determines the shape of the 1st Gaussian filter. Increases the strength and the radius of the blur of the corresponding color channel.");
             public readonly GUIContent   sssProfileStdDev2         = new GUIContent("Standard Deviation #2", "Determines the shape of the 2nd Gaussian filter. Increases the strength and the radius of the blur of the corresponding color channel.");
             public readonly GUIContent   sssProfileLerpWeight      = new GUIContent("Filter Interpolation", "Controls linear interpolation between the two Gaussian filters.");
             };
             public readonly GUIContent   sssProfileTransmission    = new GUIContent("Enable Transmission", "Toggles simulation of light passing through thin objects. Depends on the thickness of the material.");
             public readonly GUIContent   sssProfileTintColor       = new GUIContent("Transmission Tint Color", "Tints transmitted light.");
-            public readonly GUIContent   sssProfileMinMaxThickness = new GUIContent("Min-Max Thickness", "Shows the values of the thickness remap below.");
-            public readonly GUIContent   sssProfileThicknessRemap  = new GUIContent("Thickness Remap", "Remaps the thickness parameter from [0, 1] to the desired range.");
+            public readonly GUIContent   sssProfileMinMaxThickness = new GUIContent("Min-Max Thickness", "Shows the values of the thickness remap below (in centimeters).");
+            public readonly GUIContent   sssProfileThicknessRemap  = new GUIContent("Thickness Remap", "Remaps the thickness parameter from [0, 1] to the desired range (in centimeters).");
 
             public readonly GUIStyle     centeredMiniBoldLabel     = new GUIStyle(GUI.skin.label);
 
             EditorGUILayout.Space();
             EditorGUILayout.LabelField(styles.sssTransmittancePreview0, styles.centeredMiniBoldLabel);
             EditorGUILayout.LabelField(styles.sssTransmittancePreview1, EditorStyles.centeredGreyMiniLabel);
+            EditorGUILayout.LabelField(styles.sssTransmittancePreview2, EditorStyles.centeredGreyMiniLabel);
             EditorGUILayout.Space();
 
             // Draw the transmittance graph.