The thermometer integrates seamlessly with any E61 group head that has an M6 thread inside. ***Hex key not included*** ***Display is refreshing every 2 seconds*** ***Backlight and display turn off after 1 minute of inactivity to save power. Touch screen to reactivate*** This system helps find the exact idle temperature of the brew group and the exact water temperature near the coffee brew point or coffee source. It also provides consistent empirical data, taking the guesswork out of the brewing process. Compared to other thermometers on the market, our thermometer has a larger display and backlight for better viewing from different angles. The installation process is simple and does not require special tools, conditions or advanced technical knowledge. Simply make sure the E61 coffee machine is turned off and cool. Replace the hexagon head on the front of the brew group with ours - no tape, sealant, cutting or adjustments required. It is important to note that the thermometer is located near the coffee wheel, approximately 1.25 inches above. Therefore, the sensor's reading may differ slightly from the actual water temperature affecting the puck. Machine manufacturer. Typically the difference comes from the angle at which the sensor is placed in the group head. Please contact us for more information.