Laboratory balances are used to measure an object’s mass to a very high degree of precision. They consist of a beam with a friction-free fulcrum, a pointer which attaches to the beam and amplifies deviation from the balance position, and fractional weights which are applied along the beam’s measuring arm. Often, the weighing pan is sealed to prevent the ingress of dust or other contaminants. Samples are maintained at room temperature to prevent the formation of air currents inside the enclosure. Other sources of error for laboratory balances include buoyancy, friction, improper miscalibration, misalignment, condensation, evaporation, gravitational abnormalities, and seismic disturbances. For best results, laboratory balances provide high readability, a broad weighting range, and a high degree of accuracy.