Position the tip of the pole on the point to be measured. The pole may be held in any direction. Simply measure the 2 prisms and the coordinates of the hidden point are calculated. The pole is the new GMP112, which is an extension to the GMP111 Mini-Prism set. Supplied with one Mini-Prism and an adjustable extension pole. Used in conjunction with the Hidden Point Applications available on the TPS800 and TPS1200. A low-cost solution with high precision.