It's a one inch SS throddle body spacer that makes the intake air move into a "helix" (tornado) fashion. Suppose to decrease combustion time (or increase, whatever is better) and give better gas milage and apparently in some applications up to a 20+hp increase (whateverthe****ever.) They're $80 right now on eBay. I got about a +20MPT gain, which I guess is about 1mpg.