I had many hours working with these guys especially the srf10 in the above picture; I had to learn about the I2c bus communication to get it running. I did find code for it finally on the wiring website there is code from the wire. class that makes bus communication a snap but you have to down load the arduino 06 if you want to call the class in arduino. the other sensor the sense ez is a real plug and play sensor and the focal area of the sound cone is very narrow and really accurate i can't recommend this sensor enough. i will post the code when i finish writing it but it is very simple to use. the srf10 has a much bigger range but it detects anything in a 180 degree sweep from center up to three feet on the sides and below it so you have to either really point it up or raise it three feet off the ground. not so good for my application.