The Testo Sensor LD Ultrasonic Pro + Leak Detector is designed to identify and document pressurized gas leaks in industrial applications including compressed air, gas, steam, vacuum, and refrigeration systems. Operating at 40 kHz ±2 kHz, the device converts inaudible ultrasonic frequencies generated by escaping gases into audible signals delivered through sound-proof headphones, enabling detection in noisy environments. The integrated camera captures and stores visual documentation of leak locations, while an integrated laser pointer (645-660 nm, <1 mW) provides precise targeting. The system meets ASTM E1002-05 Class I instrument requirements for ultrasonic leak testing. The detector features a 3.5-inch touchscreen interface and provides direct on-screen display of leakage rates in liters per minute. Automatic level adjustment optimizes sensitivity to ambient conditions while filtering background noise, with minimum detection capability of 0.1 l/min at 6 bar pressure from 5 meters distance. The unit operates for 9 hours continuously on rechargeable lithium-ion batteries with a 4-hour charging time, and functions across an operating temperature range of 32 to 122°F. Data logging is supported through a 2 GB SD memory card.