The MAPfrac® Initiator Valve is a hydraulically activated, differential sleeve that provides the first point of entry and communication to the formation in the completion string. Generally located just above the float equipment, when opened can be used to stimulate the lower most zone of the wellbore or just as an exit port to pump down the 1st frac ball for the first stage frac operation. This compact, modular design allows for ease in handing on the rig floor and a selective opening pressure than can be adjusted on location.