http://www.amazon.com/exec/obidos/tg/detail/-/B000065DKJ/002-5324388-0377661?
v=glance
The fan sits inside the regular screen in the window now.
Not familiar with those units specifically, but I have a Holmes twin fan
(electronic thermostat and either fan can intake/exhaust). I suppose they
assume that you have window screens if you need them (since they fit
about flush in a double hung window).
When I was in an apartment with slider windows, I used a longer unit which
had a filter (with long squirrel cage fan), but that was not as effective
at moving air.
--
David Efflandt - All spam ignored http://www.de-srv.com/
If you don't have screens in your windows (why not?), you can always buy
screen material at your local hardware store and attach it to the fan
yourself. On the outside would be better; otherwise you'll get dead bugs
accumulating inside the fan box.
This won't be perfect, though, beause you'll still likely have small
gaps around the sides. Use lots of duct tape?