The TPI metal prism assembly features a 0/-30 mm constant prism system, nickel-plated-brass 5/8 x 11 mounting thread, tension-adjusting brass knob with metal holder and target. The prism can be mounted in either 0 or -30 mm offset positions. Padded carrying/storage bag is included. Fully compatible with leading manufacturers such as Sokkia, Topcon, Pentax, Nikon, Trimble, Leica etc.