http://www.ricoh-imaging.co.jp/japan/products/lens/k/converter/lc-1_4x-aw/
The official on-sales date in the Japanese home-market will be March 7th. A full list of compatible Pentax K-mount digial lenses is provided, note that not every DA lens of Pentax/Ricoh is compatible.
Besides, it does look very familiar for its appearance specs including the physical parameters, many things are just too close to my ancient "Tamron" Pz (Power Zoom) TC 1.4X Model MC-4 that I purchased 14 years ago, which is yet believed to be original manufactured by Kenko!
For more information of the Tamron 1.4X MC4, look here:
http://www.ebay.co.uk/itm/Tamron-F-AF-Tele-Converter-1-4X-Pz-AF-MC4-with-box-and-papers-/121171067435
Well, even the lens release lever looks exactly the same, what a "co-incidence"! :-o ;-)
But I just wonder, why it takes so long for Pentax to release such an OEM product, if it really is, which has been delayed for so many years since it was first announced back to 2008!?!
Nonetheless, my prolonged experience for that adapter is that it is great for APS-C cropped image circle but is just fair to rather mediocre optically when it works with Full Frame, no matter film or digial. Enough said! :-(
BTW, for real photo samples for how the "Tamron" 1.4X MC4 performs optically, here you will find some samples of mine:
K-5D Mark III: DA 18-55 II Converted to a 24-80 FULL FRAME Lens!