diff --git a/README.md b/README.md
index 0f144be..c785c93 100644
--- a/README.md
+++ b/README.md
@@ -57,7 +57,7 @@ Methods to activate motors are:
 - `angled(angle, speed_primary, speed_secondary)` - makes motor to rotate to specified angle, `angle` value is integer degrees, can be negative and can be more than 360 for several rounds
 - `stop()` - stops motor at once, it is equivalent for `constant(0)`
 
-Parameter `speed_secondary` is used when it is motor group of `motor_AB` running together. By default, `speed_secondary` equals `speed_primary`.
+Parameter `speed_secondary` is used when it is motor group of `motor_AB` running together. By default, `speed_secondary` equals `speed_primary`. Speed values range is `-1.0` to `1.0`, float values.
 
 All these methods are synchronous by default, means method does not return untill it gets confirmation from Hub that command has completed. You can pass `async=True` parameter to any of methods to switch into asynchronous, which means command will return immediately, without waiting for rotation to complete. Be careful with asynchronous calls, as they make Hub to stop reporting synchronizing statuses.
 
diff --git a/setup.py b/setup.py
index 50967c9..5366e4a 100644
--- a/setup.py
+++ b/setup.py
@@ -2,7 +2,7 @@ from distutils.core import setup
 
 setup(name='pylgbst',
       description='Python library to interact with LEGO Move Hub (from Lego BOOST set)',
-      version='0.3',
+      version='0.4',
       author='Andrey Pokhilko',
       author_email='apc4@ya.ru',
       packages=['pylgbst'],