Will RBC123 fit Back UPS 1500 Pro?

Question

Uninterruptable power source

Hello! There is this uninterruptible https://www.computeruniverse.ru/info.asp?id=90447489 . There was a need to change the battery. I looked, the main recommended replacement is a set of APC RBC124 batteries. However, finding it for sale proved difficult. Extremely similar to it are APC RBC123 batteries. Their difference is in the capacity parameter (for RBC124 - 9 Ah, RBC123 - 7 Ah). There is an assumption that this is not too critical and can be interchanged. Is it so? And do I understand correctly that if yes, then this will only affect the battery life parameter when switching work to it?