Testo 115i Wireless Pipe Clamp Thermometer with Smart Technology Suitable for pipes with diameters of 0.25 in. to Maximum 1.5 in. (6.25 mm to 38.1 mm) Ideal for temperature measurements of pipes in heating and cooling systems Integrated NTC sensor provides greater accuracy and stability than thermocouples Bluetooth connection allows for measurement data to be conveniently transmitted to Smart device equipped with Testo's Smart Probes App Identifies temperature changes by monitoring real-time trending and data logging