when you put it on your xbox 360 slim, it tends to make the internal fan in the xbox alter its settings. this will be detected when you do the may 19th update. the update will show the xbox as a tampered/modded/3rd party repair. this voids the warranty. do NOT under any circumstances put it on your 360 slim if you love your xbox and its warranty.
just thought i'd put out a friendly warning.
most stores are now aware of this issue (i.e. gamestop) and no longer sell it. however, i would beware of people trying to sell this on craigslist and other places like amazon and sites like that.