Yeah - I got one about a month ago.
If its the Juwell attachment then it fits over the filter pipe extruding from
the internal filter, with the air hose sticking above the surface level.
Mine works really well, a constant stream of bubbles blowing into the tank,
and you can direct the flow.
The good thing is its light, fairly cheap and doesn't need its own power source -
water being pumped out of the filter draws air down the hose, resulting in a good healthy flow of bubbles.
I'm really pleased with the simplcity and effectiveness of it.