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This time-of-flight sensor is a laser distance sensor, that emits a 940nm laser. It can measure distance up to 125cm quite accurate. Adafruit delivers a ready-to-use library and a functional example you should try.
The sensor is connected via I2C. So you have to use pin 4 and 5 on the Arduino Uno/Nano (other Arduinos may have different pins for I2C). It works with 3.3 volts. But since the breakoutboard has a voltage regulator implemented, you can connect it also to 5 volt.
=> work in progress
Where to buy? You can find it on eBay, if you search for "Time of flight" Or directly from Amazon: Time of flight
Original project page