I want the 2nd gen. intel 160GB for my MBP 13". But I've seen two variations of the product code. SSDSA2MH160G2C1 SSDSA2MH160G2R5 What's the difference? I have seen the R5 variation in stock a few places, but not the C1. I want to order one, while they are still in stock. But I don't want to buy the wrong product.