Those devices are manufactured by Onyx too. But casadellibro.com is not an Onyx agent or distributor. Those devices are rebranded Onyx devices for an ebook content provider...They use their own software and AFAIK it will be impossible to install the regular Onyx software, our PDF Reader, FB Reader and Cool Reader to those devices.
The selling model is similar to Amazon - you will be able to use content of the seller only. This is why those devices are slightly cheaper than ours. The device price is also offered without additional accessories - they must be purchased separately.