I use both the slide-bolt latch with a caribeaner through the hole (you can find them with holes on the larger ones) and the "flap" type that go over a u-shaped piece, again with a caribeaner through the u-shape (wish I knew the name). The caribeaners are spring type, I keep losing them, wish they were cheaper! My "human" doors have two latches, one in the middle and one by the bottom corner to keep anything from prying open that corner. I had the screw on caribeaners and hated them, I also can't imagine having any kind of lock--would drive me bonkers! If anyone has had a raccoon open a slide bolt secured by a caribeaner, I would love to know....