The thermometer seamlessly integrates with any E61 group head featuring an M6 thread inside.***Allen key not included ******Display refreshes every 2s******The background light and display turns off after 1 mintue of inactivity for the purpose of energy saving. Touch the screen to re-activate it***The system helps investigate the precise idle temperature of the group head and accurate water temperature near the brew point or coffee puck. It also furnishes consistent, empirical data, eliminating guesswork from the brewing process. Compared with other thermometers in the market, our thermometer features with a bigger display and background light allowing better veiwing from different angles.Installation is a straightforward process that requires no special tools, conditions, or advanced technical expertise. Simply ensure the E61 coffee machine is powered off and cooled. Replace the Allen head on the front of the group head with our product-no tape, sealant, cutting, or adaptations necessary.It's important to note that the thermometer is positioned near the coffee puck, approximately 1.25" above. Consequently, the sensor readings may slightly differ from the actual water temperature impacting the puck. To obtain a more realistic extraction temperature, consider adding a maximum of 2 degrees Celsius to the readings.Readings may vary depending on your coffee machine's construction type and espresso machine manufacturer. Typically, differences arise from the angle at which the sensor is inserted into the group head.For any additional information, please feel free to reach out to us.