diff --git a/dbdpy/__pycache__/__init__.cpython-39.pyc b/dbdpy/__pycache__/__init__.cpython-39.pyc
index 0b6e4c8c..8c2830fb 100644
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diff --git a/dbdpy/__pycache__/device.cpython-39.pyc b/dbdpy/__pycache__/device.cpython-39.pyc
index 7b79cfe7..c4799158 100644
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diff --git a/dbdpy/device.py b/dbdpy/device.py
index 602244d3..4dff74b5 100644
--- a/dbdpy/device.py
+++ b/dbdpy/device.py
@@ -4,13 +4,39 @@ def __init__(self, brand, model):
         self.model = model
 
     def get_device_info(self):
-        return f"{self.brand} - {self.model}"
+        """Retrieve brand and model name of a device.
 
-    # def calculate_rescale_value(self, age, is_damaged):
-    #     initial_value = 1000
-    #     depre_rate = 0.20 if self.brand == "Apple" else 0.15
-    #     rescale_value = initial_value * ((1 - depre_rate) ** age)
-    #     if is_damaged:
-    #         rescale_value *= 0.70
+        Paramters
+        ---------
+        None
 
-    #     return round(rescale_value, 2)
+        Returns
+        -------
+        device_info : str
+        """
+        device_info = f"{self.brand} - {self.model}"
+        return device_info
+
+    def calculate_rescale_value(self, age, is_damaged):
+        """Short descreption
+
+        Long description
+
+        Parameters
+        ----------
+        age : int
+            Description for parameter
+        is_damaged : bool
+            Description
+
+        Return
+        ------
+
+        """
+        initial_value = 1000
+        depre_rate = 0.20 if self.brand == "Apple" else 0.15
+        rescale_value = initial_value * ((1 - depre_rate) ** age)
+        if is_damaged:
+            rescale_value *= 0.70
+
+        return round(rescale_value, 2)
diff --git a/setup.py b/setup.py
index 28a4b77f..9325d1a6 100644
--- a/setup.py
+++ b/setup.py
@@ -1,7 +1,8 @@
 from setuptools import setup, find_packages
 
 VERSION = "0.0.1"
-DESCRIPTION = "Python package for preprocessing and analyzing wearable device data"
+DESCRIPTION = "Python package for preprocessing and \
+              analyzing wearable device data"
 
 setup(
     name="dbdpy",
diff --git a/tests/__pycache__/__init__.cpython-39.pyc b/tests/__pycache__/__init__.cpython-39.pyc
index 2f1d4eef..935c7b29 100644
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diff --git a/tests/__pycache__/test_device.cpython-39-pytest-7.1.2.pyc b/tests/__pycache__/test_device.cpython-39-pytest-7.1.2.pyc
index 4dfbad87..53159803 100644
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diff --git a/tests/test_device.py b/tests/test_device.py
index 9b763188..9955dbe7 100644
--- a/tests/test_device.py
+++ b/tests/test_device.py
@@ -18,3 +18,16 @@ def test_get_device_info():
 # def test_calculate_rescale_value(brand, age, is_damaged, expected):
 #     dev = device.CommercialDevice(brand, "AnyModel")
 #     assert dev.calculate_rescale_value(age, is_damaged) == expected
+
+
+@pytest.mark.parametrize(
+    "brand, age, is_damaged, expected",
+    [
+        ("Apple", 1, False, 800),
+        ("Apple", 2, False, 640),
+        ("Fitbit", 1, False, 850),
+    ],
+)
+def test_calculate_rescale_value(brand, age, is_damaged, expected):
+    dev = device.CommercialDevice(brand, "AnyModel")
+    assert dev.calculate_rescale_value(age, is_damaged) == expected