Product review (1 stars): it does eat batteries to the extent that you will need to have a good supply of 2032 batteries around
The most unfortunate thing about this product is that the sensor battery will run down without any notification.  So, you will have this false sense of security that the humidity is within bounds inside your instrument case until you notice within the app that the sensor hasn't reported back to the app for a week or more.  You will not have received any alert that the battery was below the low setting and that you are no longer getting notifications of any kind.  And, it does eat batteries to the extent that you will need to have a good supply of 2032 batteries around.  You're better off checking whatever means of humidification you have inside the case on a regular basis to ensure that your instrument isn't going to dry out.  I have had several instances of realizing that the sensor battery was dead without notification and finding that the humidifier inside the case had dried out.  And, this wasn't isolated to just one Humiditrak.  I can however recommend the Sensorpush, also sold on the Amazon website.  It's very reliable and the battery lasts a very long time.