The duck does have some weight to it since it requires 3 AAA batteries. It does float even with the batteries in. I had no issues with the duckymeter. The duckymeter can be a toy to keep your child entertained while it monitors the water temperature.
However, to get the full aspect of how the water temperature fluctuates I had filled the tub partially with water and allowed it to sit for a few hours just to see how cold it would get. As I added water from the faucet I could see the temperature rise quickly. As the rubber duck floats farther from the faucet, the temperature will drop. I was able to capture the changing of the temperature from cold all the way to hot within a few minutes.
I would recommend this rubber for everyone, but I also would not fully rely on it 100% since the temperature does fluctuate in different parts of the tub. Personally, I would be recommended that you still test the water out with your hands.
Once you are done make sure you dry out completely by allowing it to sit on a towel. I would also recommend checking on the battery from time to time to make sure it is working properly.
Once the LCD light starts to fade it is time to change the 3 AAA batteries(included). I was provided this product as a sample.