works! I tested it as merely an "extension" on ThinkPad T420 - on the "full sized" slot (for WWAN card or mSATA SSD) it supports extension for at least mSATA SSD (did not tested with WWAN card, but it would probably work too). On the half-sized slot (for WiFi card) it supports extension for the actual WiFi card. Presumably, it will also support extension for any other supported hardware. The point is that the actual slot on the m-b must support the intended hardware, because this one is merely an extension. For example, on the WiFi slot (not intended for mSATA) it would not support mSATA SSD, while on WWAN slot (not intended for the full mini-PCIe specification) it would not support mini-PCIe -to- full-PCIe adapters, but at the very maximum it could support only a single-port SATA extension (mSATA to regular SATA port) or USB2.0 extensions.
Excellent shipping speed. Thank you!