Ohaus 1550-SD [80000004] Harvard Trip Beam Balance, 2000 g x 0.1 g. With a two-pan design based on the classic Roberval balance principle, The Ohaus 1550-SD Harvard Trip balances feature the additional advantages of magnetic damping, beams with sliding weights and a variety of weighing platforms. Commonly used for comparative weighing to determine the difference in mass between two objects, rather than their absolute value, the 1550SD balance comes equipped with built-in sliding masses. Harvard Trip balances are known for their accuracy and durability