Battery kit for APC Smart UPS 450/600/700 replaces APC RBC5
APC Back-UPS ES 450 G (BE450G) Compatible Replacement Battery Kit : Electronics - Amazon.com
Vintage APC Backups 450 | eBay
APC APC BackUPS 6 Outlets 450VA 255W 6-Outlet 180 Joules 255-Watt 450va AC Surge Protector with Battery Backup in the Surge Protectors department at Lowes.com
APC BACK UPS 450 6V 12Ah UPS Battery - This is an AJC Brand Replacement - Newegg.com