Standard height is for everyday use. Vehicle will squat down to motorway setting after 30 seconds at above 50 mph will return to standard after 30 seconds below 35 mph. Access height is self explanatory. Extended height is for wading below 35 mph, vehicle will return to standard height if 35 mph is exceeded in extended setting. Extra extended is used automatically if chassis is grounded and is not selectable. Tow is recommended to be done with vehicle locked in standard height. There are also lockable crawl settings in access mode.