The advanced SitePro 9300N nitrogen (N2) sealed 0/-30mm prism system features a single tilting assembly with front lever locking mechanism to secure in position.  This hi-performance prism system, precisely positioned in hi-grade aluminum holder ensures accurate measurement and is best for surveying.  Dual-sided aluminum target 6.9″x5.5″ (17.6 cm x 14 cm)   62mm precision ground glass, up to 2 arc second accuracy Nitrogen sealed prism canister 5/8-11 stainless steel bayonet adapter (female thread) Aircraft-grade aluminum yoke and holder Color: Orange target with white 0/-30mm offset constant Special formulated thermo-plastic resin provides protection and longevity Warranty: 90 days