Not sure of exact specs, its about 800VA but it works alot better than other ones i have had.
I have 2 power boards (with 6 sockets in each) powering, a monitor, comptuer (550W PSU), cordless phone, amplifyed 2.1 speakers, Modem, other chargers, printer and other shit and its lasted about 25mins.
Im sure it would last about 1hour powering a fish tank pump or longer