The Attentive Sphinx is designed to meet the highest demands for accuracy and portability that professional users in the mining and tunnelling industry put on a measuring instrument of this type. With the Attentive Sphinx, you can test any installed bolt. The adapter sleeve grips around the head of the bolt when you set up the equipment and without having to prepare a bolt for pull testing prior to installation. In fact, you can even easily pull test bolts installed a long time ago. You can pull-test bolts with or without face plates.