diff --git a/app/Models/Plugin.php b/app/Models/Plugin.php
index fc49f3c..d377956 100644
--- a/app/Models/Plugin.php
+++ b/app/Models/Plugin.php
@@ -192,12 +192,8 @@ class Plugin extends Model
             $httpRequest = Http::withHeaders($headers);
 
             if ($this->polling_verb === 'post' && $this->polling_body) {
-                $contentType = (array_key_exists('Content-Type', $headers))
-                    ? $headers['Content-Type']
-                    : 'application/json';
-
                 $resolvedBody = $this->resolveLiquidVariables($this->polling_body);
-                $httpRequest = $httpRequest->withBody($resolvedBody, $contentType);
+                $httpRequest = $httpRequest->withBody($resolvedBody);
             }
 
             try {
diff --git a/public/mirror/index.html b/public/mirror/index.html
index ef60a19..64746fe 100644
--- a/public/mirror/index.html
+++ b/public/mirror/index.html
@@ -39,6 +39,7 @@
         var data = trmnl.getSettings();
         trmnl.ui.apiKeyInput.value = data.api_key || "";
         trmnl.ui.baseURLInput.value = data.base_url || "";
+        trmnl.ui.macAddressInput.value = data.mac_address || "";
         trmnl.ui.displayModeSelect.value = data.display_mode || "";
 
         trmnl.ui.setup.style.display = "flex";
@@ -49,6 +50,7 @@
 
         var apiKey = trmnl.ui.apiKeyInput.value;
         var baseURL = trmnl.ui.baseURLInput.value;
+        var macAddress = trmnl.ui.macAddressInput.value;
         var displayMode = trmnl.ui.displayModeSelect.value;
 
         if (!apiKey) {
@@ -58,6 +60,7 @@
         trmnl.saveSettings({
           api_key: apiKey,
           base_url: baseURL,
+          mac_address: macAddress,
           display_mode: displayMode
         });
 
@@ -81,6 +84,7 @@
         var apiKey = setup.api_key;
         var displayMode = setup.display_mode;
         var baseURL = setup.base_url || "https://your-byos-trmnl.com";
+        var macAddress = setup.mac_address || "00:00:00:00:00:01";
 
         document.body.classList.remove("dark", "night")
         if (displayMode) {
@@ -88,7 +92,8 @@
         }
 
         var headers = {
-          "Access-Token": apiKey
+          "Access-Token": apiKey,
+          "id": macAddress
         };
 
         var url = baseURL + "/api/display";
@@ -205,6 +210,10 @@
             hasOverrides = true;
           }
 
+          if (key === "mac_address" && value) {
+            newSettings.mac_address = value;
+            hasOverrides = true;
+          }
         }
 
         if (hasOverrides) {
@@ -265,6 +274,7 @@
         // settings
         trmnl.ui.apiKeyInput = document.getElementById("api_key");
         trmnl.ui.baseURLInput = document.getElementById("base_url");
+        trmnl.ui.macAddressInput = document.getElementById("mac_address");
         trmnl.ui.displayModeSelect = document.getElementById("display_mode");
         trmnl.ui.setup = document.getElementById("setup");
 
@@ -459,6 +469,12 @@
       <img src="/mirror/assets/logo--brand.svg" alt="TRMNL Logo" />
 
       <form onsubmit="return trmnl.saveSetup(event)">
+        <fieldset>
+          <label for="mac_address">Device MAC Address</label>
+          <input name="mac_address" id="mac_address" type="text" placeholder="00:00:00:00:00:01" class="form-control"
+            required />
+        </fieldset>
+
         <fieldset>
           <label for="api_key">Device API Key</label>
           <input name="api_key" id="api_key" type="text" placeholder="API Key" class="form-control" required />
diff --git a/resources/views/livewire/devices/configure.blade.php b/resources/views/livewire/devices/configure.blade.php
index f46b1d9..4c9b4c5 100644
--- a/resources/views/livewire/devices/configure.blade.php
+++ b/resources/views/livewire/devices/configure.blade.php
@@ -559,7 +559,7 @@ new class extends Component
 
                 <flux:modal name="mirror-url" class="md:w-96">
                     @php
-                        $mirrorUrl = url('/mirror/index.html') . '?api_key=' . urlencode($device->api_key);
+                        $mirrorUrl = url('/mirror/index.html') . '?mac_address=' . urlencode($device->mac_address) . '&api_key=' . urlencode($device->api_key);
                     @endphp
 
                     <div class="space-y-6">
diff --git a/tests/Unit/Models/PluginTest.php b/tests/Unit/Models/PluginTest.php
index 82813d9..749fb62 100644
--- a/tests/Unit/Models/PluginTest.php
+++ b/tests/Unit/Models/PluginTest.php
@@ -72,27 +72,6 @@ test('updateDataPayload sends POST request with body when polling_verb is post',
            $request->body() === '{"query": "query { user { id name } }"}');
 });
 
-test('updateDataPayload sends POST request with body with correct content type when not JSON content', function (): void {
-    Http::fake([
-        'https://example.com/api' => Http::response(['success' => true], 200),
-    ]);
-
-    $plugin = Plugin::factory()->create([
-        'data_strategy' => 'polling',
-        'polling_url' => 'https://example.com/api',
-        'polling_verb' => 'post',
-        'polling_body' => '<query><user id="123" name="John Doe"/></query>',
-        'polling_header' => 'Content-Type: text/xml'
-    ]);
-
-    $plugin->updateDataPayload();
-
-    Http::assertSent(fn ($request): bool => $request->url() === 'https://example.com/api' &&
-           $request->method() === 'POST' &&
-           $request->hasHeader('Content-Type', 'text/xml') &&
-           $request->body() === '<query><user id="123" name="John Doe"/></query>');
-});
-
 test('updateDataPayload handles multiple URLs with IDX_ prefixes', function (): void {
     $plugin = Plugin::factory()->create([
         'data_strategy' => 'polling',