The UPS R3000 XR is said to be the smallest and most power efficient 3000VA rack-mount uninterruptible power system (UPS). Designed for customers who want to provide power protection in space-constrained rack enterprise environments, it delivers 2700W and includes both hot-swap batteries and hot swap electronics. The entire UPS measures just 2U (3 1/2 inches) and weighs in at 40% less than typical models. Compaq Computer Corp.