Synergys LKSFLEX400 External Ultrasonic Flexible Sensor with Cable, 400mm. Synergys LeakShooter External Ultrasonic Flexible Sensor with Cable. Comes in 400mm and 1500mm lengths. When working in awkard areas the Flex probe is the perfect solution when accessing very small connectors. The flexible sensor can be used with both the Manual and Auto functions. Use the flexible probe to find the leak and the camera to document it.