Model E40 is an excluder with a one way door for 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. This excluder measures 4 x 4 x 12" and is designed to fit over 4 x 4" or smaller openings. It is constructed of heavy duty 1/2" x 1" - 14 gauge wire mesh.