Schneider Electric
“The APC web site was a wee tad confusing, so I bought a wrong battery. FYI boring details, older RS 1500 UPS models do not take RBC33 replacement batteries, they take older batteries model APCRBC109 . Anyway, I chatted with an APC agent, and they are sending me a FREE battery of the correct type! So these are good and reputable sellers here!”