diff --git a/SabreTools.Models/PKZIP/UnknownExtraField.cs b/SabreTools.Models/PKZIP/UnknownExtraField.cs
new file mode 100644
index 0000000..b590c1b
--- /dev/null
+++ b/SabreTools.Models/PKZIP/UnknownExtraField.cs
@@ -0,0 +1,15 @@
+namespace SabreTools.Models.PKZIP
+{
+    /// <summary>
+    /// This represents any unknown extras fields that are either
+    /// unmapped or undiscovered. All unknown header IDs map to
+    /// this data type.
+    /// </summary>
+    public class UnknownExtraField : ExtensibleDataField
+    {
+        /// <summary>
+        /// 
+        /// </summary>
+        public byte[]? Data { get; set; }
+    }
+}
\ No newline at end of file