Size: This vent bag are designed to fit 4inch diameter dryer vent pipe, 4inch diameter vent elbow and 4inch dryer vent hood with rain cover. Package includes: 3 pack of vent bags. The vent hood is not included. Convenient to use: No other items such as string, clamp, magnets, wire or screw be needed if you use our vent cover bags. The hook and loop fasteners would do the job. Design: Made of polyester fiber mesh. The opening of the bags is sewn with loop strips which help you quickly put these vent bags on or off the vent rain cover. Application: the problem of birds' nests or dryer lint dust. The lint bags can not only catch the lint but also allow proper venting.