This devices is actually a self-made hardware project which came with a book called "Amiga Hardware Tuning". The PCB was supplied only. This device can be used as a RAM disk, as an EPROM "hard drive" or as a non-volatile RAM disk as it can be powered by a NICaf Battery. A maximum of 1MB can be used. The device is auto-configurable and can be even used to boot from.
Thanks to Sebastian Breitkeuz