Please Please Please be very carefull in this warmer weather your windows should be fitted with screens if you plan to have them opened, even just a little or your Bengal Babies will escape if you are careless :-(  

You can either make or buy inexpensive window screens 

Link below is from Flat Cats a very good and reasonable company mention you have cats from Summerspride for your discount :-) 

http://www.flat-cats.co.uk/flat_cats_slideshow.htm