You can use the card to display all OCS pal (50Hz) and ntsc (60 Hz) modes in lowres, hires, hires interlaced on a vga monitor. Monitor has to be able to display 50Hz!
The other ECS and AGA modes can cause trouble with it. It works in A4000 too. But the slot does not fit.
As mentioned it scandoubles 15khz to 30khz and "deinterlaces" interlace modes.