Ultrasonic Sensor 5 PCS Distance Sensor Kit with Jumper Wires, Compatible with Arduino, Raspberry Pi, Datasheet Available to Download

Good value for money, especially if you are a 'Prime' member!

These sensors are great for distance measuring with many small microcontroller projects. It's worth noting they require 5v (not 3.3v) therefore a bit trickier to use with the likes of ESP8266. It's worth noting it works intermittently with 3.3v but will be unreliable.

Works perfectly with a raspberry pi using python but you will have to accept the accuracy limitations which in my care is +/- 3cm's. Depending on the application you may also need a couple of resistors to limit the return voltage, plenty of online resources that explain what and how and cost less than 30p from Maplins.

I use these to measure water level. Connected to an Arduino mega. A short 1 line (map) code can convert the distance into a litre measurement. Very handy.

Perfect exampe of budget ultrasonic sensors works out the box with many arduino examples

Works really well. Don't expect perfect readings though without some good error correction code in your sketch (for Arduino). Particularly if bouncing off of something like skin instead of a hard material - the signal can become very jittery.

Great Value for money, nicely made, so far all three of the units I've wired up have functioned correctly

Must be used with 5V, not 3.3V. As long as they get a 5V supply, they worked correctly the first time, with NewPing library on Arduino or New_Ping on Particle Photon. Accurate to about 1cm.