No problem with shopping or delivery, although as there is a big choice deciding which cat flap can be a problem. I ordered a Staywell PetSafe 400 Deluxe Magnetic Cat Flap and an extension tunnel to fit it in a single brick wall. It seems quite well made and does the job it is meant to. I cut out the wall as the template and the tunnel fits in well. Now the problems; There is no means to secure the cat flap on the inside of the wall and no clue in the instructions. I had to dismantle the inner cover (not much of a problem it just clips off) and drill some fixing holes. Screw the cat flap to the wall and reassemble. It is only designed to clamp to whatever it is passing though but by adding the tunnel the screws are not long enough. They would have to be 5 or 6 inches long. The tunnel extension is supposed to be glued in place, this is not supplied and no clue is given as to what type of glue to use. I used UHU but a solvent plastic cement would be better. There are holes and blanking plugs for the outside cover, so just drill the wall and fix. The problem is there is an unsightly gap between the cover and the end of the tunnel if the tunnel were a little bit longer this would not matter so much but as it is there is gap enough to see the brickwork. I will fill this with white silicon sealant but dot think I should have to. All in all it works OK but not a job for the feint hearted.