<https://www.factoryforward.com/product/hcsr04-ultrasonic-sensor-module/#product>
<http://schema.org/description>
"Operating voltage: +5V\r\n \tTheoretical  Measuring Distance: 2cm to 450cm\r\n \tPractical Measuring Distance based on surface: 2cm to 80cm\r\n \tAccuracy: 3mm\r\n \tMeasuring angle covered: &amp;lt;15°\r\n \tOperating Current: &amp;lt;15mA\r\n \tOperating Frequency: 40Hz"
<https://www.factoryforward.com/product/hcsr04-ultrasonic-sensor-module/>