Turns out there are two form factors for this UPS Model number

I ordered this battery using the model number on my UPS

Nearly impossible to find a useful model number on the PDU.

This battery pack is an OEM replacement that worked for my APC Back-UPS XS 1500.It was confusing trying to find the correct battery, as APC seems to have used this model number for a few very similar UPS units.

This battery pack is advertised to fit my UPS system by specific model number (BX1500LCD / Back-UPS 1500XS).

After some back-and-forth explaining that I was looking at the correct UPS model number and type but the battery would not work, I surmised that maybe APC changed the UPS in a newer version of the same model number but didn't tell anyone.

seemed like nice batteries, but wound up dropping them off to be recycled as I misread my model number (XS1500 rather than what is listed for these).

Perfect replacement for my APC UPS BX1500M; and, extremely easy to replace

Perfect replacement for my APC UPS BX1500M; and, extremely easy to replace