I prefer 160's. Skunks have small and seemingly very protected windpipes. A 120 has always given me neck catches, which for most animals is a quick and humane kill but I have not found that to be the case with skunks. This year I ran all 155's and 160's and preferred the 160's for the simple reason that even that the extra inch of a 160 gave me a complete suitcase catch (one bar on the head/neck and the other bar on the chest) on almost every skunk I caught in them. Rarely did they even move the trap out of the box. 120's and even the 155's gave me more neck and a few chest catches but very few suitcase catches. A neck caught skunk is not going to die very quickly and is likely to spray during the struggle. I'm not saying that all of my 160 caught skunks had full pods of essence but I know for a fact those skunks did not live very long after being caught.