The HC-SR04 Ultrasonic Range Finder is a very good product for learning about another sensor mechanism in the world of robotics. Had so much fun developing the code for my robot. After the Arduino Micro-controller read a value great than 3000, it went into a routine, backed up, turned and went on its way. Has a little trouble with chair and table legs and big stuffed teddy bears for the money I give it a strong 4 stars.
