These worked great for Rats. Even smart ones were caught . It's easy to place the bait from the bottom and then open the trap till it clicks. The size of the opening is large on these traps so they can catch larger prey like squirrels. But the jaws are also very big and could really injure a pet or person!! So do not allow kids or pets anywhere near them!! One trick i used to make sure my dogs wouldn't find them is to put them inside a 12 pack of coke case. They fit snug and you have to set the trap 1st so be very very careful . Open both ends of the case and put it where you want it out of the way where pets can't reach but rodents can and slide the set trap in and close the back tabs. You can try to gently tape them or have tape already on them so you just have to carefully close and tape shut. I used mozzarella cheese sticks and just pinched off a small piece to use for bait. With these big traps you have to use something that smells like strong cheese but you need to push it down into the cup and really try to get it soft enough to stick. Peanut Butter did not work as well, they were able to lick it off without putting their hands or head on the traps' plate. If you use peanut butter use a q tip to put it inside the cup without getting much on the sides , you want them to have to reach their hands and head in deep to ensure capture. It kills them instantly and leaves no blood. Then it's super easy to take the trap outside, they stink terribly if you throw them in the trash. I throw them over the fence for nature to use.