This is a replaceable battery cartridge to be used with APC's Back-UPS 250 UPS and Back-UPS 280 UPS (BK280B). American Power Conversion (APC) back-up batteries are user-replaceable and hot swappable. This allows users to swap batteries without any downtime for the units. The batteries ship in a reusable carton to ship the exhausted battery to any APC recycling center. A typical battery should last for three to six years.