Moved to a new apartment in No Cal and I thought living on the 2nd floor would provide my cat a safe place to hang out. Well twice now a neighbor's cat or alley cat has pulled off a Spiderman. First the alley cat jumps on the neighbors a/c unit, then the low wall, then jumps up onto my patio's beam, up onto my a/c, which gives the alley cat full access to my balcony. My cat had a low growling face off with the alley cat about a week ago. Since then, I've kept my cat on the a short lease. Doggy door access effectively closed until I figure out a solution.

I thought I could put a scat mat on my a/c, which as I said is the alley cat's final jump off point. Well it'd be a long way down for the other cat, but oh well.

Anyone have one and has found it effective?