The "double locking" adapter is this flexible plastic which twists itself
at highway speed until the adapter is fully opened by the airflow. The
blade is now free to slide downward from the friction of blade against the
glass. It will generally fully unhook itself and toss itself into the
median leaving the steel hook grinding against your windshield after 8 to10
minutes. This I'm supposing is the 'evolution" part. Warning: Use these
wipers only when nearing an exit.