Make sure you wear the rubber gloves first. Then tear off the protect film on each side of Dust Cover.
Keep wearing the gloves. Put Dust Cover into the Window Cover and align the straight part of them. There is no front side or back side issue for Dust Cover.
Keep wearing the gloves. Push Window Cover with Dust Cover into the rubber holes on Front Cover. Press all the rubber teeth from the inner to the outside.
Dust Cover is firm and can not separate after completed assembly.