Abstract: A two piece blind fastener for securing a plurality of workpieces including a hollow sleeve having an enlarged sleeve head at one end and a pin having an enlarged shear ring at the end opposite the sleeve head followed by an elongated retention portion of reduced diameter. The shear ring is adapted to engage and move inside the sleeve to form a tuliped shaped blind head in response to a relative axial force applied between the pin and sleeve and to shear off proximate to the inner or blind sheet line of the workpieces. The retention portion is then moved with the pin shank into the shear ring and with the shear ring finally located at a position on the retention portion depending upon the overall thickness of the workpieces. This provides a clamp and lock section between the pin and sleeve at the inner or blind side of the workpieces. The pin and sleeve have a lock structure actuated after final formation of the clamp and lock section to provide a lock between the pin and sleeve.