The Silent Sentry Uninterruptible Power Supply from OnStat Power, Inc., of Stamford, Connecticut, is a battery-operated, wall-mounted system that has space-saving and labor-saving features. The new low-profile design can be mounted on or between wall studs with a protrusion of less than 4 1⁄2 inches. It is available as a standalone or hardwired unit. The hardwired design features a built-in subpanel with branch-circuit protectors. Power supplies are particularly useful in providing backup power for high-rise buildings or facilities where generators are impractical, and come in 2000- and 3100-watt models.