1.there is window in back but no for the old series ;there is no window in the bottom.But there are for the old ones.These will not let urine spray out from the carrier.
2.The bottom conects with the top use plastic clips .This make the user much easier when assembling.Srews holes were kept in the carrier.You can use the screws to make it safer when you travelling in the airline.
3.we use the wire to make the window for the two biggest carrier to make the door not chew the window.
4、There are wheels for the two biggest size .And two handles for these two size
