Barometer Pressure Temperature Altitude Sensor BMP180
Wonder how much barometric pressure there is outside a flying plane? Then you could use this sensor in simulating barometric pressure level in relationship with altitude.
This sensor is the next-generation BMP085, with a better marginal error of +/- 0.12 in measuring altitude but with the same pressure unit used.
It can sense pressure that ranges from 300hPa to 1100Pa and can measure altitude from 9000 meters above and 500 meters below sea level. It can be powered with 3.3V to 5V power supply and can be interfaced with your Arduino using the I2C pins (SDA/SCL).