I installed the MM Cat Door on Friday after work, I have to say it was very easy to remove the old standard cat door & replace it with the MM Cat Door. Our cat has taken to the door with ease. It’s was a bit weird for him to begin with as he was used to just running & jumping at the old cat door. He realises that he will get in so has just kept at it and can make it thru in the first or second go now.It has stopped the neighbors cat coming into our house and eating our cat’s food & SPRAYING everywhere. I have heard a thud when the other cat has tried to enter but it has been over a week now and there is no sign of the other cat. It has worked exactly how I had wished. Thank you for your help.