This popular Catchmaster small mouse traps is approximately 4" x 1 3/4" each. There are four mouse traps total in each pack. The mouse trap is disposable or you can reuse it. The mouse trap has a wooden board with plastic bait trigger plate. Just place the mouse trap where the mouse has been seen. The mouse trap is non-toxic, easy to use, and quick to kill. If you don't catch anything within a few days, switch to a different food as some food works better than other.