Abstract: An apparatus for casting an anchor in a concrete unit in which the head of the anchor is gripped by a plurality of resiliently-biased gripper elements pivotally attached to a cylindrical mandrel, the mandrel is drawn within the bore of a void former sleeve having a hemispherical outer end, and the sleeve is withdrawn within the channel of a support sleeve attached to associated formwork such that the hemispherical outer end protrudes from the formwork. After the concrete unit is cast, the void former sleeve is withdrawn from the unit so that the outer end leaves a hemispherical void in the unit and the mandrel is disengaged from the head of the anchor, leaving the head exposed within the void. The support sleeve includes a spring-loaded detent pin which is positioned to engage detent slots in the void former sleeve and a detent recess in the mandrel to hold the sleeve and mandrel in position during casting and to hold the sleeve in position as the anchor is attached to the mandrel.