Question about APC Back-UPS AVR, IEC

Hello community - I have 2 of these devices running (in the office and at home) and now the battery from the first one is gone... Can anyone tell me which replacement battery I should order? I can't find one in the accessories section and there are various specifications on the Internet, which can hardly all be correct... If you would advise me not to replace the battery and rather buy a new device, I am open to reasons and suggestions, as these are no longer available here. Thanks for your help in advance!