The PK K'1 measures a mere 16.8 mm long by 16 mm wide by 7 mm deep. By comparison, SanDisk's Ultra Fit USB 3.0 drives measure 19.1 mm by 15.9 mm by 8.8 mm. PKParis' drive looks a bit slicker as well (based on product shots), with a rectangular aluminum body that could fit nicely into a MacBook chassis. It also includes a little cord for attaching to a keychain. PKParis is claiming transfer speeds of up to 140 MB/s, similar to SanDisk's 130 MB/s transfer speeds.
PKParis doesn't have a long track record. We've never sampled any of its products, and the 64GB version of its tiny thumb drive has just a few user reviews on Amazon (one good, one average, one bad). If you're mesmerized by that angular, aluminum design, PKParis will gladly take your pre-order for $112--a 20 percent discount off its $140 list price--before shipping in September.
SanDisk has the advantage of being an established brand. Its Ultra Fit drive users get a copy of SecureAccess for creating password-protected folders with 128-bit AES encryption, along with a year's subscription to RescuePro for recovering corrupted or accidentally deleted files. SanDisk should start selling its 128GB Ultra Fit drive soon.
Why this matters: Scoff at the diminutive nature of these USB drives if you will, but size matters if you're looking to add semi-permanent flash storage to a laptop or game console. An established brand is important too, though, especially when it comes to data integrity, and SanDisk has an edge there.