Warning that "compatible" battery requires modification (a "flash") BIOS of the laptop (so that the battery is recognized by him). Flashing is a potentially risky operation that can make the PC completely unusable if it fails ... Sony (or other) does not provide the existing BIOS backup solution prior to flashing. The economy can therefore be very expensive ... Note valid for all compatible Sony batteries (which locks its too !! products). Not wanting to take any risks, I returned the product to PTS, actual repayment 10 days after the referral. So overall Honourable logistics services. It remains to find an original battery at a reasonable price!