diff --git a/adafruit_hts221.py b/adafruit_hts221.py
index 2f32030..1aac71c 100644
--- a/adafruit_hts221.py
+++ b/adafruit_hts221.py
@@ -34,6 +34,12 @@
 from adafruit_register.i2c_bits import RWBits, ROBits
 from adafruit_register.i2c_bit import RWBit, ROBit
 
+try:
+    from typing import Union, Sequence, Tuple
+    from busio import I2C
+except ImportError:
+    pass
+
 _WHO_AM_I = const(0x0F)
 
 _CTRL_REG1 = const(0x20)
@@ -65,21 +71,21 @@ class CV:
     """struct helper"""
 
     @classmethod
-    def add_values(cls, value_tuples):
+    def add_values(
+        cls, value_tuples: Sequence[Tuple[str, int, Union[int, float]]]
+    ) -> None:
         """creates CV entries"""
-        cls.string = {}
-        cls.lsb = {}
+        cls.label = {}
 
         for value_tuple in value_tuples:
-            name, value, string, lsb = value_tuple
+            name, value, label = value_tuple
             setattr(cls, name, value)
-            cls.string[value] = string
-            cls.lsb[value] = lsb
+            cls.label[value] = label
 
     @classmethod
-    def is_valid(cls, value):
+    def is_valid(cls, value: int) -> bool:
         """Returns true if the given value is a member of the CV"""
-        return value in cls.string
+        return value in cls.label
 
 
 class Rate(CV):
@@ -105,10 +111,10 @@ class Rate(CV):
 
 Rate.add_values(
     (
-        ("ONE_SHOT", 0, 0, None),
-        ("RATE_1_HZ", 1, 1, None),
-        ("RATE_7_HZ", 2, 7, None),
-        ("RATE_12_5_HZ", 3, 12.5, None),
+        ("ONE_SHOT", 0, 0),
+        ("RATE_1_HZ", 1, 1),
+        ("RATE_7_HZ", 2, 7),
+        ("RATE_12_5_HZ", 3, 12.5),
     )
 )
 
@@ -170,7 +176,7 @@ class HTS221:  # pylint: disable=too-many-instance-attributes
     _h0_t0_out = ROUnaryStruct(_H0_T0_OUT, "<h")
     _h1_t0_out = ROUnaryStruct(_H1_T1_OUT, "<h")
 
-    def __init__(self, i2c_bus):
+    def __init__(self, i2c_bus: I2C) -> None:
         self.i2c_device = i2cdevice.I2CDevice(i2c_bus, _HTS221_DEFAULT_ADDRESS)
         if not self._chip_id in [_HTS221_CHIP_ID]:
             raise RuntimeError(
@@ -203,14 +209,14 @@ def __init__(self, i2c_bus):
         self.calib_hum_meas_1 = self._h1_t0_out
 
     # This is the closest thing to a software reset. It re-loads the calibration values from flash
-    def _boot(self):
+    def _boot(self) -> None:
         self._boot_bit = True
         # wait for the reset to finish
         while self._boot_bit:
             pass
 
     @property
-    def relative_humidity(self):
+    def relative_humidity(self) -> float:
         """The current relative humidity measurement in %rH"""
         calibrated_value_delta = self.calib_hum_value_1 - self.calib_hum_value_0
         calibrated_measurement_delta = self.calib_hum_meas_1 - self.calib_hum_meas_0
@@ -228,7 +234,7 @@ def relative_humidity(self):
         return adjusted_humidity
 
     @property
-    def temperature(self):
+    def temperature(self) -> float:
         """The current temperature measurement in degrees Celsius"""
 
         calibrated_value_delta = self.calibrated_value_1 - self.calib_temp_value_0
@@ -247,7 +253,7 @@ def temperature(self):
         return adjusted_temp
 
     @property
-    def data_rate(self):
+    def data_rate(self) -> int:
         """The rate at which the sensor measures :attr:`relative_humidity` and :attr:`temperature`.
         :attr:`data_rate` should be set to one of the values of :class:`adafruit_hts221.Rate`.
         Note that setting :attr:`data_rate` to ``Rate.ONE_SHOT`` will cause
@@ -256,23 +262,23 @@ def data_rate(self):
         return self._data_rate
 
     @data_rate.setter
-    def data_rate(self, value):
+    def data_rate(self, value: int) -> None:
         if not Rate.is_valid(value):
             raise AttributeError("data_rate must be a `Rate`")
 
         self._data_rate = value
 
     @property
-    def humidity_data_ready(self):
+    def humidity_data_ready(self) -> bool:
         """Returns true if a new relative humidity measurement is available to be read"""
         return self._humidity_status_bit
 
     @property
-    def temperature_data_ready(self):
+    def temperature_data_ready(self) -> bool:
         """Returns true if a new temperature measurement is available to be read"""
         return self._temperature_status_bit
 
-    def take_measurements(self):
+    def take_measurements(self) -> None:
         """Update the value of :attr:`relative_humidity` and :attr:`temperature` by taking a single
         measurement. Only meaningful if :attr:`data_rate` is set to ``ONE_SHOT``"""
         self._one_shot_bit = True
diff --git a/examples/hts221_simpletest.py b/examples/hts221_simpletest.py
index 2dd96d4..d34e64f 100644
--- a/examples/hts221_simpletest.py
+++ b/examples/hts221_simpletest.py
@@ -8,8 +8,12 @@
 i2c = board.I2C()
 hts = adafruit_hts221.HTS221(i2c)
 
+data_rate = adafruit_hts221.Rate.label[hts.data_rate]
+print("Using data rate of: {:.1f} Hz".format(data_rate))
+print("")
+
 while True:
-    print("Relative Humidity: %.2f %% rH" % hts.relative_humidity)
-    print("Temperature: %.2f C" % hts.temperature)
+    print("Relative Humidity: {:.2f} % rH".format(hts.relative_humidity))
+    print("Temperature: {:.2f} C".format(hts.temperature))
     print("")
     time.sleep(1)