Possibly sound a bit dodgy to me. Or could be an imported version. Just had a look at the Bosch UK website and they only list 2 different 36V li ion batts....they be the 1.3 or 2.6Ah versions. No mention of Premium or Standard or anything similar.
I have had my big Bosch now for approx 4 yrs and batteries, ahem, cells, are still going strong.. though they do seem more sluggish in colder weather a little this year.
There are a plethora of the Bosch 36V 2.6Ah batts on the web, many different looking/coloured/labelled than what I have. So I would say some are either cheap imports or fake perhaps.