diff --git a/src/LLM.php b/src/LLM.php
index 4927301..ad32537 100644
--- a/src/LLM.php
+++ b/src/LLM.php
@@ -16,7 +16,7 @@
 
 final class LLM implements LLMInterface
 {
-    protected array $defaultOptions = [
+    private array $defaultOptions = [
         Option::Temperature->value => 0.8,
         Option::MaxTokens->value => 120,
         Option::TopP->value => null,
@@ -27,7 +27,7 @@ final class LLM implements LLMInterface
         Option::FunctionCall->value => null,
         Option::Functions->value => null,
         Option::User->value => null,
-        Option::Model->value => 'gpt-4o-mini',
+        Option::Model->value => OpenAIModel::Gpt4oMini->value,
     ];
 
     public function __construct(
diff --git a/src/OpenAIModel.php b/src/OpenAIModel.php
new file mode 100644
index 0000000..6c1803a
--- /dev/null
+++ b/src/OpenAIModel.php
@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LLM\Agents\OpenAI\Client;
+
+enum OpenAIModel: string
+{
+    case Gpt4o = 'gpt-4o';
+    case Gpt4oLatest = 'chatgpt-4o-latest';
+    case Gpt4o20240513 = 'gpt-4o-2024-05-13';
+    case Gpt4o20240806 = 'gpt-4o-2024-08-06';
+
+    case Gpt4oMini = 'gpt-4o-mini';
+    case Gpt4oMini20240718 = 'gpt-4o-mini-2024-07-18';
+
+    case Gpt4Turbo = 'gpt-4-turbo';
+    case Gpt4TurboPreview = 'gpt-4-turbo-preview';
+
+    case Gpt4 = 'gpt-4';
+    case Gpt40613 = 'gpt-4-0613';
+
+    case Gpt3Turbo = 'gpt-3.5-turbo';
+    case Gpt3Turbo1106 = 'gpt-3.5-turbo-1106';
+    case Gpt3TurboInstruct = 'gpt-3.5-turbo-instruct';
+}
\ No newline at end of file