525VA Standby UPS system, around 90 minutes runtime.

The MINUTEMAN MN 525 is a 525VA/275W 120 VAC stand-by UPS with 3 surge/backup, 3 surge-only outlets, power management software, and modem/fax surge protection. Features:

• Power management software to safely close files and shutdown computer.
• Transformer-friendly spacing of outlets for connecting multiple AC adapters
• 6 outlets (3 UPS battery backup and surge protection outlets, 3 surge-only outlets)
• 3-year warranty for electronics (2-year warranty for batteries)
• MINUTEMAN Platinum Protection Plan insures equipment for up to $40,000 (U.S. and Canada).

With a Talkswitch or Bizfon and a music on hold system, this UPS should last around 1.5 hours.