It was a stick in hair extension (sticks to your scalp) that my hairdressers did for breast cancer week, hence the bright pink! But they come in all colours from blue, green, blonde right through to purple and black.
They last about 4 weeks, and can easily be removed by rubbing hair conditioner into the glue. They are real hair too so they can be straightend etc.
Have a look in my photo albums and you'll see I have a blonde one in at the mo
Have a look at this website, it has good info on them