Tribrach Adapter W Optical Plummet Surveying Tribrach with Optical Plummet Adjust Screw in Left Hand for Sokkia Topcon Style

A tribrach is an attachment plate used to attach a surveying instrument, for example a theodolite, total station, GNSS antenna or target to a tripod. A tribrach allows the survey instrument to be repeatedly placed in the same position over a surveying marker point with sub-millimetre precision, by loosening and re-tightening a lock to adjust the instrument base in a horizontal plane. The device consists of two triangular metal plates connected at their corners by leveling thumbscrews, a bubble level, a locking mechanism and often an optical plummet. The centre of the bottom plate of the tribrach has a 5/8-11 UNC thread bolt hole which is used to attach the tribrach to the tripod. The top plate has three small holes or slots spaced 120? apart above leveling thumbscrews and a locking mechanism which enables a survey instrument or target to be accurately placed on the tribrach and locked in place.