Amazon.com: Liebert GXT4 Hot Swap Internal 48V, 5 Ah Lead Acid Battery GXT4 Line Interactive UPS Systems from 500-1000VA, Replacement Battery for Uninterruptible Power Supply(GXT4-5A48BATKIT) : Electronics
Liebert UPStation GXT GXT1500RT-120 12V 7Ah UPS Battery - This Is an AJC Brand Replacement - Walmart.com
Liebert UPS Station GXT3 replacement battery pack (rechargeable, high rate)
Installing Batteries in a Liebert GXT2-2000RT120 UPS « Keith's Electronics Blog