diff --git a/src/exercicses/ex_d_bis/StepThread.java b/src/exercicses/ex_d_bis/StepThread.java
new file mode 100644
index 0000000..b1218c2
--- /dev/null
+++ b/src/exercicses/ex_d_bis/StepThread.java
@@ -0,0 +1,36 @@
+package exercicses.ex_d_bis;
+
+public class StepThread extends Thread {
+    private int i;
+    private String startMsg;
+    private String endMsg;
+    private long duration;
+    private Thread dependency;
+
+    public StepThread(int i, String startMsg, String endMsg, long duration, Thread dependency) {
+        this.i = i;
+        this.startMsg = startMsg;
+        this.endMsg = endMsg;
+        this.duration = duration;
+        this.dependency = dependency;
+    }
+
+    @Override
+    public void run() {
+        if (dependency != null) {
+            try {
+                dependency.join();
+            } catch (InterruptedException e) {
+                throw new RuntimeException(e);
+            }
+        }
+
+        System.out.println("Stage " + i + ": " + startMsg);
+        try {
+            Thread.sleep(duration);
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+        System.out.println("Stage " + i + ": " + endMsg);
+    }
+}
diff --git a/src/exercicses/ex_d_bis/TestStepThreads.java b/src/exercicses/ex_d_bis/TestStepThreads.java
new file mode 100644
index 0000000..ee267b3
--- /dev/null
+++ b/src/exercicses/ex_d_bis/TestStepThreads.java
@@ -0,0 +1,30 @@
+package exercicses.ex_d_bis;
+
+public class TestStepThreads {
+    public static void main(String[] args) {
+        Thread rawMatPrep = new StepThread(
+                1,
+                "Preparing raw materials...",
+                "Completed raw materials preparation.",
+                1000,
+                null
+        );
+        Thread assembly = new StepThread(
+                2,
+                "Assembling the product...",
+                "Completed product assembly.",
+                2000,
+                rawMatPrep
+        );
+        Thread qualityCtrl = new StepThread(
+                3,
+                "Quality control...",
+                "Quality control completed.",
+                500,
+                assembly
+        );
+        rawMatPrep.start();
+        assembly.start();
+        qualityCtrl.start();
+    }
+}