Nasty little rats.  2 nights.  4 traps.  2 rats.  I bought 4 traps, some of them are a little hard to set, but they work great.  I do recommend 2 modifications: (1) Make a slit in water bottle lid (along part of the side parallel to the flat round part of the lidP.  You can then slide it over the copper bait holder to make a tub style bait holder.  This allows you to stuff the lid full of peanut butter and jam a piece or two of dog food in there so that rodents have to dig or lick out the tub --- sure to set off the trap.  (2) I screw my traps to the end of a 2 ft to 2.5 ft 2x4 or other piece of flat wood so that the rats can't take off with the traps (like they have done for me before)... and so they can be emptied without ever getting near the rat.  The metal spring part of all four of my traps sticks out far enough that it is easy to catch it on a rock or stick to open it (from the distance of the 2x4).