diff --git a/css/main.css b/css/main.css
index f082ec2..38977ce 100644
--- a/css/main.css
+++ b/css/main.css
@@ -780,6 +780,34 @@ header .search form input[type='submit'] {
 	border: none !important;
 }
 
+/* Tooltip container */
+.tooltip {
+    position: relative;
+    display: inline-block;
+}
+
+/* Tooltip text */
+.tooltip .tooltiptext {
+    visibility: hidden;
+    width: 120px;
+    background-color: black;
+    color: #fff;
+    text-align: center;
+    padding: 5px 0;
+    border-radius: 6px;
+    text-transform: none !important;
+
+    /* Position the tooltip text - see examples below! */
+    position: absolute;
+    z-index: 1;
+}
+
+/* Show the tooltip text when you mouse over the tooltip container */
+.tooltip:hover .tooltiptext {
+    visibility: visible;
+}
+
+
 @media only screen and (min-width: 900px) {
 }
 
diff --git a/js/tracker.js b/js/tracker.js
index 4960c2c..5e3f665 100644
--- a/js/tracker.js
+++ b/js/tracker.js
@@ -1012,6 +1012,11 @@ function habitat_data(jsondata, alternative) {
     "xdata": "XDATA"
   };
 
+  var tooltips = {
+    "burst_timer": "If active, this indicates the time (HH:MM:SS) until the radiosonde will automatically power-off.",
+    "xdata": "Raw auxiliary data (as hexadecimal) from an external sensor package (often an Ozone sensor)."
+  }
+
   var hide_keys = {
     "spam": true,
     "battery_millivolts": true,
@@ -1068,11 +1073,14 @@ function habitat_data(jsondata, alternative) {
       if (hide_keys[k] === true)
         continue;
 
-      var name = "", suffix = "";
+        var name = "", suffix = "", tooltip = "";
       if (keys[k] !== undefined)
         name = keys[k];
       else
         name = guess_name(k);
+    
+      if (tooltips[k] !== undefined)
+        tooltip = tooltips[k];
 
       if (suffixes[k] !== undefined)
         suffix = suffixes[k];
@@ -1104,7 +1112,11 @@ function habitat_data(jsondata, alternative) {
       if(typeof alternative == 'boolean' && alternative) {
           output += "<div><b>" + name + ":&nbsp;</b>" + v + suffix + "</div>";
       } else {
-          output += "<dt>" + v + suffix + "</dt><dd>" + name + "</dd>";
+          if (tooltip != "") {
+            output += "<dt>" + v + suffix + "</dt><dd>" + name + ' <div class="tooltip">🛈<span class="tooltiptext">' + tooltip + '</span></div></dd>';
+          } else {
+            output += "<dt>" + v + suffix + "</dt><dd>" + name + "</dd>";
+          }
       }
     }
     return output;