Model E40D is an excluder trap with an easy release door for chipmunks, squirrels and similar size animals. Tomahawk excluders are designed to let animals remove themselves from unwanted areas. Excluders have mounting wings which allow them to be attached directly over the animals den opening. The one way door lets animals exit and prevents them from returning. The rear door allows you to trap the animal or simply remove the rear door to use it as a true excluder. This excluder trap measures 26L x 4W x 4H" and is constructed of heavy duty 1/2 x 1" - 14 gauge wire mesh. It is designed to fit over 4 x 4" or smaller openings.