the following text has been google translated off a spanish site...
"... In 2006, the brand became acquired by the Albacete company Pielcu, which began marketing and manufacturing certain models especially from Albacete with the collaboration of local cutlery companies. These units created in these years began to be known in the sector for the new marking that were included in the pieces starting the numbering by the letter "B-". Becoming known among fans of the sector as "
Aitor Pre-Pielcu ".Since the previous manufactured units were marked starting with the letter "A-", these units being highly valued today by collectors in specialized forums of the sector.
Between 2014-2015, the company was acquired again by
Rehabe SL (Current manufacturer of all Aitor parts) , being again the essence of its beginnings in Ermua (Vizcaya). Currently exporting more than 50% of its production to countries worldwide such as France, Argentina, USA, Germany, Japan, etc ..."
https://m.facebook.com/CuchillosAitor/photos/?ref=page_internal&mt_nav=0
i guess that pretty much explains it.