Abstract: An adapter for use with a conventional installation tool normally used for installing blind rivets comprises a universal installer head which is attached to the tool by threading one end of it onto the head of the tool in alignment with the gripping and pulling jaws located within the tool. The other end of the installer head is made to engage the upper surface of a squash nut. A pull shaft has a threaded end for engagement with the internally threaded portion of a squash nut and a jaw engaging end for free passage through the hole in the installer head into the area within the tool where it is gripped and pulled by the jaws in the installation tool. For squash nuts of different sizes, different pull shafts may be used where the jaw engaging end is of the same external diameter but where the threaded end has a different size depending upon the size of the squash nut with which the pull shaft is intended to be used.