diff --git a/pom.xml b/pom.xml
index 7d7349c..de8f7fd 100644
--- a/pom.xml
+++ b/pom.xml
@@ -27,14 +27,14 @@
         <dependency>
             <groupId>org.spigotmc</groupId>
             <artifactId>spigot-api</artifactId>
-            <version>1.20.4-R0.1-SNAPSHOT</version>
+            <version>1.21.4-R0.1-SNAPSHOT</version>
             <scope>provided</scope>
         </dependency>
 
         <dependency>
             <groupId>com.github.Slimefun</groupId>
             <artifactId>Slimefun4</artifactId>
-            <version>6bc1b1f474</version>
+            <version>experimental-SNAPSHOT</version>
             <scope>provided</scope>
         </dependency>
 
@@ -48,7 +48,7 @@
         <dependency>
             <groupId>org.bstats</groupId>
             <artifactId>bstats-bukkit</artifactId>
-            <version>3.0.0</version>
+            <version>3.1.0</version>
             <scope>compile</scope>
         </dependency>
     </dependencies>
diff --git a/src/main/java/dev/j3fftw/soundmuffler/SoundMuffler.java b/src/main/java/dev/j3fftw/soundmuffler/SoundMuffler.java
index a55cab4..7f8e6d7 100644
--- a/src/main/java/dev/j3fftw/soundmuffler/SoundMuffler.java
+++ b/src/main/java/dev/j3fftw/soundmuffler/SoundMuffler.java
@@ -29,7 +29,7 @@ public void onEnable() {
         }
 
         SOUND_MUFFLER = new ItemGroup(new NamespacedKey(this, "sound_muffler"),
-            new CustomItemStack(Material.BEACON, "&7SoundMuffler", "", "&a> Click to open"));
+            CustomItemStack.create(Material.BEACON, "&7SoundMuffler", "", "&a> Click to open"));
 
         new SoundMufflerListener(this).start();
 
diff --git a/src/main/java/dev/j3fftw/soundmuffler/SoundMufflerMachine.java b/src/main/java/dev/j3fftw/soundmuffler/SoundMufflerMachine.java
index 4d5dc86..30a0b92 100644
--- a/src/main/java/dev/j3fftw/soundmuffler/SoundMufflerMachine.java
+++ b/src/main/java/dev/j3fftw/soundmuffler/SoundMufflerMachine.java
@@ -37,13 +37,13 @@ public SoundMufflerMachine() {
         super(SoundMuffler.SOUND_MUFFLER,
             new SlimefunItemStack(ITEM_ID, Material.WHITE_CONCRETE, ITEM_NAME,
                 "", "&7Muffles all sound in a", "&78 block radius", "", "&e\u26A1 Requires power to use"
-            ),
+            ).item(),
             ITEM_ID,
             RecipeType.ENHANCED_CRAFTING_TABLE,
             new ItemStack[] {
-                new ItemStack(Material.WHITE_WOOL), SlimefunItems.STEEL_PLATE, new ItemStack(Material.WHITE_WOOL),
-                SlimefunItems.STEEL_PLATE, SlimefunItems.ELECTRIC_MOTOR, SlimefunItems.STEEL_PLATE,
-                new ItemStack(Material.WHITE_WOOL), SlimefunItems.STEEL_PLATE, new ItemStack(Material.WHITE_WOOL)
+                new ItemStack(Material.WHITE_WOOL), SlimefunItems.STEEL_PLATE.item(), new ItemStack(Material.WHITE_WOOL),
+                SlimefunItems.STEEL_PLATE.item(), SlimefunItems.ELECTRIC_MOTOR.item(), SlimefunItems.STEEL_PLATE.item(),
+                new ItemStack(Material.WHITE_WOOL), SlimefunItems.STEEL_PLATE.item(), new ItemStack(Material.WHITE_WOOL)
             }
 
         );
@@ -69,9 +69,9 @@ public void newInstance(@Nonnull final BlockMenu menu, @Nonnull final Block b) {
                     enabled = Boolean.parseBoolean(BlockStorage.getLocationInfo(b.getLocation(), "enabled"));
                 }
 
-                menu.replaceExistingItem(8, new CustomItemStack((enabled ? Material.REDSTONE : Material.GUNPOWDER),
+                menu.replaceExistingItem(8, CustomItemStack.create((enabled ? Material.REDSTONE : Material.GUNPOWDER),
                     "&7Enabled: " + (enabled ? "&a✔" : "&4✘"), "", "&e> Click to enable this Machine"));
-                menu.replaceExistingItem(0, new CustomItemStack(Material.PAPER,
+                menu.replaceExistingItem(0, CustomItemStack.create(Material.PAPER,
                     "&eVolume: &b" + volume,
                     "&7Valid value range: 0-100",
                     "&7L-click: -10",
@@ -125,7 +125,7 @@ public int[] getSlotsAccessedByItemTransport(ItemTransportFlow flow) {
 
     protected void constructMenu(BlockMenuPreset preset) {
         for (int i : border) {
-            preset.addItem(i, new CustomItemStack(Material.GRAY_STAINED_GLASS_PANE, " "),
+            preset.addItem(i, CustomItemStack.create(Material.GRAY_STAINED_GLASS_PANE, " "),
                 (player, i1, itemStack, clickAction) -> false);
         }
     }