You begin by turning on your faucet above the thermometer, which tracks the temperature and tells you when it's at the right comfort level for your kid. If the temperature gets too high, the screen turns red and beeps, and if it drops too low, it turns blue.
Once the temperature is right, the screen will turn green, and you can plug the bottom of the pool to let the water gather.
As the first pool fills, water is redirected through a channel into the larger tub, where your baby will be sitting. A foam pad helps kids keep traction, so even if they haven't learned to sit up yet, they'll be in a comfortable position the whole time.
The Infant Tub includes a cup for pouring warm water over any parts of your baby that aren't submerged. I found it helpful for cleaning the creases, which can be one of the big challenges of giving babies a bath.
The thermometer is connected to power on the bottom of the tub with an insulated wire.
The battery pack requires three AAA batteries -- not included with the tub. The thermometer and screen are low power, though, so the batteries should last a while.
The 4moms Infant Tub is a simple product, but cleverly designed. At $50 (about £35 or AU$70), it's not a bad investment for new parents.