Health o Meter BFM582-63 Body Fat, Percent Hydration & Weight Tracking Scale calculates body fat and hydration percentage. It accurately measures weight up to 330 lbs in 0.2 lb increments and FDA approved BIA (bioelectrical impedance analysis) measures body fat by passing tiny electrical impulses through the body. The electrical current reacts to fat and muscle by measuring resistance to the current. Has tempered 8mm glass platform with chrome accents and 1.5" backlit LCD display. Displays weight and change in weight for up to 4 users. 4 replaceable AA batteries included.