HP 826631-251 is a Russian-layout keyboard replacement for the HP EliteBook 820 G4 and 828 G4. Its part-number suffix identifies the Russian market, making it the regional keyboard option for these notebook families.
This is the non-backlit keyboard variant. It includes a pointing-stick connection for cursor control from the keyboard area. The guide lists the pointing-stick cable separately in Cable Kit 912091-001, so that cable is not confirmed as part of this keyboard.