diff --git a/ESP-IDF_Robot/tutorial/docs/source/overview.rst b/ESP-IDF_Robot/tutorial/docs/source/overview.rst
index f0540f8f8..e0d073499 100644
--- a/ESP-IDF_Robot/tutorial/docs/source/overview.rst
+++ b/ESP-IDF_Robot/tutorial/docs/source/overview.rst
@@ -28,7 +28,7 @@ In particular, **GPIO6** and **GPIO5** provide PWM to the left- and right- side
 Similarly, **GPIO4** and **GPIO7** provide PWM to the left- and right- side DC motors to rotate in a **counter-clockwise** direction.
 Changing PWM on each channel determines the speed and direction of the RC car.
 
-The following images illustrate various PWM duty cycles registered by oscilloscope.
+The following images illustrate various PWM duty cycles registered by oscilloscope (duty cycles 0%, 50% and 95%, resp.).
 
 .. image:: _static/ESP-IDF_Robot_PWM_Duty-0.bmp