The Lifeline AED and Lifeline VIEW are semi-automatic and the Lifeline AUTO is fully-automatic. With all 3 of our AEDs, the unit makes the decision of whether or not a shock is required, but the semi-automatic version asks the user to “press the flashing shock button” and will only deliver a shock when the button is pressed. The fully automatic version will automatically deliver the shock without the need for human intervention.  PLEASE NOTE – if a shock is not required the defibrillators WILL NOT allow a shock to be given.