AND Newton EJ [EJ-300] Portable Precision Balance with External Calibration, 310g x 0.01g - 110mm. The AND Weighing EJ-300 Newton EJ Portable Balance, 310g x 0.01g is affordable that offers flexible and practical performance. The EJ300 smartly optimizes counting accuracy with "ACAI" that auto improves accuracy throughout your counting procedure. The EJ300 external calibration switch and gravity acceleration correction keeps you accurate and precise.