diff --git a/documentation/pyserial_api.rst b/documentation/pyserial_api.rst
index d9dcb32..76177dd 100644
--- a/documentation/pyserial_api.rst
+++ b/documentation/pyserial_api.rst
@@ -36,7 +36,7 @@
             :const:`STOPBITS_TWO`
 
         :param float timeout:
-            Set a read timeout value.
+            Set a read timeout value in seconds.
 
         :param bool xonxoff:
             Enable software flow control.
@@ -48,7 +48,7 @@
             Enable hardware (DSR/DTR) flow control.
 
         :param float write_timeout:
-            Set a write timeout value.
+            Set a write timeout value in seconds.
 
         :param float inter_byte_timeout:
             Inter-character timeout, :const:`None` to disable (default).
@@ -237,7 +237,7 @@
 
     .. method:: send_break(duration=0.25)
 
-        :param float duration: Time to activate the BREAK condition.
+        :param float duration: Time in seconds, to activate the BREAK condition.
 
         Send break condition. Timed, returns to idle state after given
         duration.