an instrument for holding an intervertebral spacer , the instrument comprising a shaft having a proximal end and a distal end , the proximal end forming a handle and the distal end forming a spacer engaging subassembly , the spacer engaging subassembly comprising at least one selectively expanding and contracting enclosure into which at least a portion of the spacer is introduced when the engaging subassembly is expanded and an actuating mechanism , extending from the proximal end to the distal end , by which the spacer member engaging subassembly may be selectively expanded and contracted .