It's a Tanita BF-681W. I bought it at Bed Bath & Beyond last week to inspire me. The old scale was over 20 years old and lied to me, so it had to go. It's programmable for up to 4 people and also has a "guest" function. You enter your height, gender, activity level and age. It stores those facts for each person.
When you step on the electrodes on the base, it weighs you and then calculates your % body fat based on electrical impedence (fat is harder for the current to flow thru than other tissue). The current used is very small (the thing runs on 4 AA batteries) and you don't feel it. The scale also calculates your Total Body Water and the number of daily calories necessary for you to maintain that weight. Any number of calories that you consume below that number (supposedly) will result in a loss of weight.
For me, it was worth the money spent (even without a coupon) to see those numbers changing in a downward mode. I hope that as I continue to exercise, my Body Fat % will continue to fall, even if I don't see a change in my weight.