Abstract: A removable reference laser target for detachable installation at identified target positions on the exterior of a refractory lined high temperature molten metal vessel. The target includes a generally rectangular target plate with an elongated slot generally paralleling the long dimension of the rectangle. On the same side of the plate but on opposite sides of the slot are two mounting and adjusting bolts for detachably affixing the target at an identified position on the exterior surface of the vessel. Extending essentially at right angles to the major rectangular surface of the plate is an extension, the free end of which contacts an external reinforcing member and assures precise re-location of the target to be used with laser equipment to provide a reference for determining thickness and/or condition of a refractory lining of the vessel.