The cat perch was a big bigger (bulkier) than I thought - so it was too high for the window sill.  However, I moved it downstairs and put a slim cat bed on top and now all three of my furkids take turns on it (only one fits into the tunnel as it is only big enough for small, lean cats).  Overall, a great cat perch for the price.  The only deduction in "stars" is for the flimsy carpet.  Every time the cats scratch on the post, carpet pile just flies everywhere.  Sisal cover for the scratching area would have been more efficient and cats love sisal.  Maybe a recommendation for the next design. :-)