diff --git a/ README.md b/ README.md
deleted file mode 100644
index 7360054..0000000
--- a/ README.md	
+++ /dev/null
@@ -1 +0,0 @@
-AuLib
\ No newline at end of file
diff --git a/src/main/java/com/io/yutian/aulib/gui/button/ItemButton.java b/src/main/java/com/io/yutian/aulib/gui/button/ItemButton.java
index bbd2da2..3025344 100644
--- a/src/main/java/com/io/yutian/aulib/gui/button/ItemButton.java
+++ b/src/main/java/com/io/yutian/aulib/gui/button/ItemButton.java
@@ -1,5 +1,7 @@
 package com.io.yutian.aulib.gui.button;
 
+import com.io.yutian.aulib.nbt.NBTItem;
+import com.io.yutian.aulib.nbt.NBTString;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
 
@@ -18,10 +20,11 @@ public class ItemButton extends Button {
 
     public ItemButton(ItemStack itemStack) {
         super(itemStack);
-
-        NBTItem nbtItem = new NBTItem(item);
-        nbtItem.setString("gui_meta", "item_button");
-        setItemStack(nbtItem.getItem());
+        NBTItem nbtItem = new NBTItem(itemStack);
+        nbtItem.editTag((nbtCompound -> {
+            nbtCompound.putString("gui_meta", "item_button");
+        }));
+        setItemStack(nbtItem.getItemStack());
     }
 
     public ItemButton setItem(ItemStack item) {
@@ -49,7 +52,7 @@ public class ItemButton extends Button {
 
     public boolean isItem(ItemStack item) {
         NBTItem nbtItem = new NBTItem(item);
-        return nbtItem.hasTag("gui_meta", NBTType.NBTTagString) && nbtItem.getString("gui_meta").equalsIgnoreCase("item_button");
+        return nbtItem.has("gui_meta", NBTString.TYPE_ID) && ((NBTString) nbtItem.get("gui_meta")).getString().equals("item_button");
     }
 
     public ItemButton clickItem(BiConsumer<Player, ItemStack> consumer) {
diff --git a/src/main/java/com/io/yutian/aulib/nbt/NBTByteArray.java b/src/main/java/com/io/yutian/aulib/nbt/NBTByteArray.java
index 9cf5fd3..a61c438 100644
--- a/src/main/java/com/io/yutian/aulib/nbt/NBTByteArray.java
+++ b/src/main/java/com/io/yutian/aulib/nbt/NBTByteArray.java
@@ -2,7 +2,7 @@ package com.io.yutian.aulib.nbt;
 
 import java.util.Arrays;
 
-public class NBTByteArray extends INBT {
+public class NBTByteArray implements INBT {
 
     public static byte TYPE_ID = 7;
 
diff --git a/src/main/java/com/io/yutian/aulib/nbt/NBTHelper.java b/src/main/java/com/io/yutian/aulib/nbt/NBTHelper.java
index 101bdd6..7e70cc6 100644
--- a/src/main/java/com/io/yutian/aulib/nbt/NBTHelper.java
+++ b/src/main/java/com/io/yutian/aulib/nbt/NBTHelper.java
@@ -33,7 +33,7 @@ public class NBTHelper {
     }
 
     public static Object convertNMSNBT(INBT nbt) {
-        return nbt.getNMSNBT();
+        return INBT.asNMS(nbt);
     }
 
 }
diff --git a/src/main/java/com/io/yutian/aulib/nbt/NBTIntArray.java b/src/main/java/com/io/yutian/aulib/nbt/NBTIntArray.java
index b087a20..e04f2c4 100644
--- a/src/main/java/com/io/yutian/aulib/nbt/NBTIntArray.java
+++ b/src/main/java/com/io/yutian/aulib/nbt/NBTIntArray.java
@@ -1,6 +1,6 @@
 package com.io.yutian.aulib.nbt;
 
-public class NBTIntArray extends INBT {
+public class NBTIntArray implements INBT {
 
     public static byte TYPE_ID = 11;
 
diff --git a/src/main/java/com/io/yutian/aulib/nbt/NBTItemStack.java b/src/main/java/com/io/yutian/aulib/nbt/NBTItem.java
similarity index 63%
rename from src/main/java/com/io/yutian/aulib/nbt/NBTItemStack.java
rename to src/main/java/com/io/yutian/aulib/nbt/NBTItem.java
index 6b00655..12be16b 100644
--- a/src/main/java/com/io/yutian/aulib/nbt/NBTItemStack.java
+++ b/src/main/java/com/io/yutian/aulib/nbt/NBTItem.java
@@ -3,21 +3,24 @@ package com.io.yutian.aulib.nbt;
 import net.minecraft.nbt.NBTTagCompound;
 import org.bukkit.craftbukkit.v1_18_R2.inventory.CraftItemStack;
 import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
 
+import javax.annotation.Nullable;
 import java.util.function.Consumer;
 
-public class NBTItemStack {
+public class NBTItem {
 
     private ItemStack originalItemStack;
     private net.minecraft.world.item.ItemStack nmsItemStack;
 
     protected ItemStack resultItemStack;
 
-    public NBTItemStack(ItemStack itemStack) {
+    public NBTItem(ItemStack itemStack) {
         this.originalItemStack = itemStack;
         this.nmsItemStack = CraftItemStack.asNMSCopy(itemStack);
     }
 
+    @NotNull
     public NBTCompound getTag() {
         NBTTagCompound tag = nmsItemStack.u();
         if (tag == null) {
@@ -26,6 +29,22 @@ public class NBTItemStack {
         return (NBTCompound) INBT.as(tag);
     }
 
+    public boolean has(String key) {
+        NBTCompound nbtCompound = getTag();
+        return nbtCompound.hasKey(key);
+    }
+
+    public boolean has(String key, int type) {
+        NBTCompound nbtCompound = getTag();
+        return nbtCompound.hasKey(key, type);
+    }
+
+    @Nullable
+    public INBT get(String key) {
+        NBTCompound nbtCompound = getTag();
+        return nbtCompound.hasKey(key) ? nbtCompound.get(key) : null;
+    }
+
     public void editTag(Consumer<NBTCompound> consumer) {
         NBTCompound tag = getTag();
         consumer.accept(tag);
@@ -49,13 +68,13 @@ public class NBTItemStack {
         return nmsItemStack;
     }
 
-    public static NBTItemStack build(ItemStack itemStack) {
-        return new NBTItemStack(itemStack);
+    public static NBTItem build(ItemStack itemStack) {
+        return new NBTItem(itemStack);
     }
 
-    public static NBTItemStack build(NBTCompound nbtCompound) {
+    public static NBTItem build(NBTCompound nbtCompound) {
         net.minecraft.world.item.ItemStack nmsItemStack = net.minecraft.world.item.ItemStack.a((NBTTagCompound) INBT.asNMS(nbtCompound));
-        return new NBTItemStack(CraftItemStack.asBukkitCopy(nmsItemStack));
+        return new NBTItem(CraftItemStack.asBukkitCopy(nmsItemStack));
     }
 
 }
diff --git a/src/main/java/com/io/yutian/aulib/nbt/NBTList.java b/src/main/java/com/io/yutian/aulib/nbt/NBTList.java
index 2bbde58..488513a 100644
--- a/src/main/java/com/io/yutian/aulib/nbt/NBTList.java
+++ b/src/main/java/com/io/yutian/aulib/nbt/NBTList.java
@@ -3,7 +3,7 @@ package com.io.yutian.aulib.nbt;
 import java.util.ArrayList;
 import java.util.List;
 
-public class NBTList<T extends INBT> extends INBT {
+public class NBTList<T extends INBT> implements INBT {
 
     public static byte TYPE_ID = 9;
 
diff --git a/src/main/java/com/io/yutian/aulib/nbt/NBTLongArray.java b/src/main/java/com/io/yutian/aulib/nbt/NBTLongArray.java
index 5231ee7..221ca91 100644
--- a/src/main/java/com/io/yutian/aulib/nbt/NBTLongArray.java
+++ b/src/main/java/com/io/yutian/aulib/nbt/NBTLongArray.java
@@ -1,6 +1,6 @@
 package com.io.yutian.aulib.nbt;
 
-public class NBTLongArray extends INBT {
+public class NBTLongArray implements INBT {
 
     public static byte TYPE_ID = 12;
 
diff --git a/src/main/java/com/io/yutian/aulib/nbt/NBTString.java b/src/main/java/com/io/yutian/aulib/nbt/NBTString.java
index 0c35e12..b20d99d 100644
--- a/src/main/java/com/io/yutian/aulib/nbt/NBTString.java
+++ b/src/main/java/com/io/yutian/aulib/nbt/NBTString.java
@@ -1,6 +1,6 @@
 package com.io.yutian.aulib.nbt;
 
-public class NBTString extends INBT {
+public class NBTString implements INBT {
 
     public static byte TYPE_ID = 8;