diff --git a/src/pocketmine/network/mcpe/protocol/types/SkinAdapter.php b/src/pocketmine/network/mcpe/protocol/types/SkinAdapter.php
index 7904917fb..56b940063 100644
--- a/src/pocketmine/network/mcpe/protocol/types/SkinAdapter.php
+++ b/src/pocketmine/network/mcpe/protocol/types/SkinAdapter.php
@@ -25,9 +25,24 @@ namespace pocketmine\network\mcpe\protocol\types;
 
 use pocketmine\entity\Skin;
 
+/**
+ * Used to convert new skin data to the skin entity or old skin entity to skin data.
+ */
 interface SkinAdapter{
 
+	/**
+	 * Allows you to convert a skin entity to skin data.
+	 *
+	 * @param Skin $skin
+	 * @return SkinData
+	 */
 	public function toSkinData(Skin $skin) : SkinData;
 
+	/**
+	 * Allows you to convert skin data to a skin entity.
+	 *
+	 * @param SkinData $data
+	 * @return Skin
+	 */
 	public function fromSkinData(SkinData $data) : Skin;
 }
\ No newline at end of file
diff --git a/src/pocketmine/network/mcpe/protocol/types/SkinAdapterSingleton.php b/src/pocketmine/network/mcpe/protocol/types/SkinAdapterSingleton.php
index 38a928e6e..b75f228b3 100644
--- a/src/pocketmine/network/mcpe/protocol/types/SkinAdapterSingleton.php
+++ b/src/pocketmine/network/mcpe/protocol/types/SkinAdapterSingleton.php
@@ -23,8 +23,11 @@ declare(strict_types=1);
 
 namespace pocketmine\network\mcpe\protocol\types;
 
+/**
+ * Accessor for SkinAdapter
+*/
 class SkinAdapterSingleton{
-
+	/** @var SkinAdapter|null */
 	private static $skinAdapter = null;
 
 	public static function get() : SkinAdapter{
@@ -34,7 +37,7 @@ class SkinAdapterSingleton{
 		return self::$skinAdapter;
 	}
 
-	public static function set(SkinAdapter $adapter){
+	public static function set(SkinAdapter $adapter) : void{
 		self::$skinAdapter = $adapter;
 	}
 }
\ No newline at end of file