Fastskin3 or Arena powerskin pro carbon ?

I want to buy next week a new kneeskin but witch is better ?

Are there some different's ? And where i can buy this ?

THX for the answers, your Emily

" Definitely advantage Arena Powerskin Carbon Pro vs Speedo Fastskin 3. Hannah Miley, Fran Halsall and Sarah Sjostrom all wore the new Arena suit and threw down the most impressive swims of the competition." http://speedendurance.blogspot.ch/2012/03/fran-halsall-equals-inge-de-bruijns.html?showComment=1343576409359#c813809836657197958