The Sure Test? GroGuru Base (Collector) is used to collect data from the various Stems (sold separately) with sensors. The Base then forwards this information to the cloud. A single Base can be used to communicate with up to 1,000 Stems depending on deployment. This is powered by an indoor-rated 110 V power supply. Simply plug it in and it is ready to go. Download the app: iOS/Android phone/tablet. The app makes it possible for you to see trends and set thresholds to generate automated alerts.