You can use your scale as often as you want, all measurements will be transmitted and appear on our website in real-time. You can use it once a week, every day, or even multiple times per day. However, we do recommend using it once a day always at the same time. Right after you wake up for example. The success of our product is not just about measuring your weight, it is about the support that we give you based on these measurements. We will replace your scale if it's not working properly within 12 months after purchase. It comes with everything you need to use it. Batteries are included, so it will be ready to use as soon as you open the box. There is absolutely no setup process or installation. You need to step on it. It turns off automatically. The UNIT button on the bottom of the scale change from Lb to Kg. It is not waterproof. Only one person can use a given scale, so if there are more members of the family that want keep track of their weight, then using multiple scales is the way to go. We recommend Duracell batteries since our tests have shown that they last longer then regular batteries. You need 4 of them for your scale. Maximum weight: Calibrated for 180 kg (397 lb). Accuracy:+/- 0.1 kg (0.2 lb)