This expanded, plastic trigger rat snap trap is a lot more sensitive than the normal metal trigger style.
Place traps on a hard surface, perpendicular to a wall so that the trigger end is toward the wall.
Traps should be set in areas where there is high activity such as fresh droppings, gnawings, rub marks, burrows, or urine stains. When trapping, whether you use glue traps, snap traps or live traps, the key is to be persistent and aggressive with the trapping. You may need more traps than you think is warranted. Rats are often shy of new objects and placing unset traps in a new location for a few days will increase the opportunities of catching.