Name：rear view parking sensor with speech Model：SN-818(SN-808) Product Introducation： Features: 1) Display type: LED display 2) Sensor number: 4 3) Detector type: adhesive or built-in 4) 3-digital distance display 5) Car hands free kit 6) Numeral sectional record and play 7) Activation: a) Rear sensors are activated when the reverse gear is engaged b) Distance will be voiced when it reaches 1.5m, 0.6m and 0.3m and obstacle will be shown on the display c) When you are backing the car, the rear sensors will detect obstacles behind the car automatically d) Stage-by-stage sound alarm to avoid collisions with adjustable volume and mute setting