They come with a key to open them. If you order some TIE A PIECE OF WIRE TO THE KEY AND TIE THE OTHER END TO A STICK OF FIREWOOD SPRAY PAINTED ORANGE. Or else you will have to use a screw driver to pry them open at risk of stabbing yourself and getting rat guts in the wound. It is nice that they have a locking feature, (it's just a cheezy little plastic tab, but there are two of them) you can put them right in the coop.
Hahahaha....that's really good advice as I've lost anything that could possibly be lost that I just knew I wouldn't lose and would remember where I put it.

So...do you think using bacon grease or anything similar will actually attract rats into a barn that they aren't currently inhabiting?
Do chipmunk's have the same taste?