HY-SRF05 SRF05 Ultrasonic Distance Sensor Module 5Pin DC 5V for Arduino UNO Replace SR04 Electronic Brick Compatible Interface: Amazon.com: Industrial & Scientific
US-100 Ultrasonic Sensor Module DC 24V - 5V with Temperature Compensation Range Distance 450cm for Arduino: Amazon.com: Industrial & Scientific
Amazon.com: Ardest Measuring Module Ranging Ultrasonic Distance Sensor for Obstacle Avoidance in Arduino Projects Pack of 2 by Ardest : Industrial & Scientific
Amazon.com: WYPH Ultrasonic Module HC-SR04 Distance Measuring Ranging Sensor for Arduino UNO for Mega R3 Duemilanove Nano Robot Pack of 10pcs : Industrial & Scientific
Amazon.com: 2pcs Ultrasonic Sensor Module HC-SR04 for Arduino, Distance Sensors with 2pcs Mounting Bracket Compatible with Mega2560, Robot kit, for ZigBee (2) : Industrial & Scientific