This product here. Good price/performance ratio and in stock. However, it is USB 3.0 and not Thunderbolt. Otherwise you can also pay the extra price for Thunderbolt and just have to wait for the product. It also depends a little on the application.

@Brimstone, thanks for the reply. I chose the Lacie Rugged Thunderbolt (2000gb), but it is very slow, why? Maybe I'm the one who can't take advantage of it. Would be nice to get an answer from you.