Leica GDF311 Tribrach without Plummet The Leica GDF311 Tribrach is a  precision mounting base from the Professional 3000 Series , designed for stable setup of surveying instruments, delivering  high rigidity, reliable leveling, and consistent field accuracy  for total station workflows. Built without an optical plummet, it is optimized for streamlined setups where external centering methods are used. Engineered for demanding field conditions, the GDF311 features  large-diameter foot screws for smooth fine adjustment , even when wearing gloves, and provides high torsional stiffness to ensure stable instrument positioning during measurement operations. Key Features • Professional tribrach for  stable TPS instrument mounting and leveling • Suitable for instruments with  angular accuracy greater than 3″ • Large foot screws for  precise adjustment in field conditions with gloves • High torsional stiffness of  < 3″ for improved measurement stability • Designed for  surveying, construction, and control point applications