diff --git a/ArduCopter/APM_Config.h b/ArduCopter/APM_Config.h
index 02f78394cc..382578a31d 100644
--- a/ArduCopter/APM_Config.h
+++ b/ArduCopter/APM_Config.h
@@ -17,12 +17,21 @@
  *  HELI_FRAME
  */
 
-// uncomment the lines below to save on flash space if compiling for the APM using Arduino IDE
-//#define OPTFLOW               DISABLED            // disable optical flow sensor to save 5K of flash space
-//#define LOGGING_ENABLED       DISABLED            // disable dataflash logging to save 11K of flash space
-//#define MOUNT                 DISABLED            // disable the camera gimbal to save 8K of flash space
+// uncomment the lines below to save on flash space if compiling for the APM using Arduino IDE.  Top items save the most flash space
 //#define CLI_ENABLED           DISABLED            // disable the CLI (command-line-interface) to save 21K of flash space
+//#define LOGGING_ENABLED       DISABLED            // disable dataflash logging to save 11K of flash space
+//#define GPS_PROTOCOL          GPS_PROTOCOL_UBLOX  // hard code GPS to Ublox to save 8k of flash
+//#define GPS_PROTOCOL          GPS_PROTOCOL_MTK19  // hard cdoe GPS to Mediatek to save 10k of flash
+//#define MOUNT                 DISABLED            // disable the camera gimbal to save 8K of flash space
 //#define AUTOTUNE              DISABLED            // disable the auto tune functionality to save 7k of flash
+//#define OPTFLOW               DISABLED            // disable optical flow sensor to save 5K of flash space
+//#define AC_FENCE              DISABLED            // disable fence to save 2k of flash
+//#define CAMERA                DISABLED            // disable camera trigger to save 1k of flash
+//#define COPTER_LEDS           DISABLED            // disable external navigation leds to save 1k of flash
+//#define CONFIG_SONAR          DISABLED            // disable sonar to save 1k of flash
+
+// features below are disabled by default
+//#define SPRAYER               ENABLED             // enable the crop sprayer feature (two ESC controlled pumps the speed of which depends upon the vehicle's horizontal velocity)
 
 // redefine size of throttle deadband in pwm (0 ~ 1000)
 //#define THROTTLE_IN_DEADBAND   100