Let me preface this post with if you can use a 160 or a 220 then do it. It is legal when set within the proper bounds to use a 160 here in PA. However a 120 will catch and kill any coon that sticks it's head in. One year I had all my 160's in use and tried the 120's. I did catch coon but noticed that I got a lot of refusal's. I was using the 120 in a dug in box opening (Outlaw set) as described by Tom Krause. Please buy his book if you want the set description. After watching this refusal I started changing my baiting methods. No more eels or fish for bait, I used only fresh marshmallows and PBJ sandwiches with as much bait outside of the box as inside. It did not eliminate refusals entirely but in my opinion increased the catch rate. The only problem was traps needed to be securely fastened as I started getting bears sticking their paws in and getting caught. The largest coon I have ever caught was in a 120 set and baited as described. Also, I set the trigger to the side and bent backwards, always check when doing this that the trigger does not contact the roof of the box before going off. I still set all my 160's first but will set the 120's if needed.