The  trimble style 360 degree prism assembly features seven 25.4mm silver-coated prisms and incorporates a protective rubber bumper on the exterior ring. The built in bulls-eye bubble helps keep the prism level when used with a stakeout point. The prism has zero offset and 5/8 X 11 mounting thread. Storage case included. This prism is compatible with all robotic total station; Trimble, Topcon, Sokkia, Leica etc.