diff --git a/docs/PID tuning.md b/docs/PID tuning.md
index 6e586bb84..c29b1f215 100644
--- a/docs/PID tuning.md	
+++ b/docs/PID tuning.md	
@@ -32,6 +32,8 @@ set too high, the craft will oscillate (but with slower oscillations than with P
 
 *Note that TPA is set via CLI or on the PID TUNING tab of the GUI.  tpa_breakpoint is set via CLI*
 
+Also note that TPA and tpa_breakpoint may not be used in certain PID Contorllers.  Check the description on the individual controller.
+
 TPA applies a PID value reduction in relation to full Throttle. It is used to apply dampening of PID values as full throttle is reached.
 
 **TPA** = % of dampening that will occur at full throttle.