So, a friend of mine has this little device that he carries with him. Its a small "L" shaped device with two ends. On one end you slide it over your valve stem. The other end you pop in a small cartridge of compressed air and it will fill up your tire to finish your ride or make it to an air pump.

What is this device called? What other tips/ tricks should I know for dealing with flats on a long stretch of deserted road?