I bought 'hail screen', a strong welded wire mesh with 1/4x1/4 holes and had it stapled to the outside of the window frames. Our home has old fashioned raise and lower windows on the inside and storm windows with regular metal screening on the outside. The hail screen was stapled on the outside directly to the wooden window frame. This way I can open the windows and if the ferrets scratch through the window screen they can't scratch through the hail screen. I had the hail screen put on all our windows. The ferrets enjoy laying in the window sills particularly when there is a soft breeze and when I turn the attic fan on! When we lived in a mobile home that was metal, we built wood frames and stapled the hail screen to the frame then used screws to attach the frames around the windows. hugs to all. tle Troy Lynn Eckart, F.B.S. Ferret Family Services http://www.ferretfamilyservices.org http://www-personal.ksu.edu/~sprite/ffs.html http://www.geocities.com/Petsburgh/Haven/5481/ Please sign up to support our efforts http://www.iGive.com/FFS [Posted in FML issue 4498]