Unidirectional BV 520T TFT will detect the blood flow average velocity. The main features of the product will detect the blood stream status of arterial/venous by 8.0MHz. It has doppler frequency 100 7000Hz. Battery has 7.4V/900mAhrechargeable and lithium input voltage DC 9V 1000mA. The product connected with high speed USB port that can be connected directly to computer to analyze, store, and print the waveform. It has choose menu by pressing keys, store 50 curves. It has ultrasonic frequency with 8.0MHz10%. It can delect the pulse rate and show PR simultaneously PPG probe for option. Built-in ARM microprocessor and real time displays blood flow velocity waveform. It can be utilized to listen the temporo mandibular joints , assist doctor to check the conditions of the joints and predict the result of treatment.