AND Gemini GR [GR-300] Analytical Balance with Internal Calibration, 310g x 0.1mg - 85mm Ø . The AND Weighing Gemini GR-300 Analytical Balance, 310g x 0.1mg with Internal Calibration features splash proof membrane keypad, a large LCD display, and space saving footprint. The GR300's stable die cast aluminum base with built-in internal weight performs automatic self-calibration. The GR300 is easy to operate, clean, and maintain.