The RAM-B-121-TD1U consists of a yoke clamp base, double socket arm and cradle for the Trimble TDS Recon. The RAM yoke clamp mount will fit rails from 0.625" to a maximum of 1.25". Designed into the mount is a 1" diameter patented rubber ball and socket system with adjustment points at the base and cradle. With a twist of the arm knob, you can move the yoke clamp mount to your optimum viewing position.