This is great for containing my 18 pound pug.  I purchased the X-Small 24" height.  She cannot jump over it or knock it over.  The stabilizers help hold the shape in place.  I bought it to use on vacation to keep her from getting into things while I was eating meals or getting ready.  It worked great indoors!  She had room to play with her toys in the pen.  I have not tried it outside yet, but I plan to.  Also, the pen folds flat and has a clip to hold it together for easy storage.