If your Doctor SF6 not buy from us, then your SF6 bios version maybe old. Then you need to buy this bios to upgrade your SF6 to latest v6.21

It is easy to upgrade, open your SF6 bios cover (no need screw driver)
Replace new bios, then close SF6 bios cover. Finished.

Very old SF6 need to open the case, because it don't have bios cover.

This Bios is 27C512 EPROM.