Selkirk Metalbestos 4RV-2 4-Inch X 24-Inch RV Gas Vent Round Pipe Selkirk is the most trusted name in insulted venting products. Used by professionals and homeowners alike for over 60 years. Selkirk continues to produce and develop innovative and safe products. Features Manufactured in United states Easy to use Highly durable Designed for use on approved gas appliances in residential and light industrial application Involves incorporating a LockTab in the female end of each gas vent section a accessories The incorporation of a LockTab feature simply improves our lock system by adding flexibility and meeting market needs Gives installer the option of engaging the LockTab instead of using sheet meal screws Round pipe design USA SHIPPING estimates delivery times and we work to get your item to you as quickly as possible and within those times, but please know it may take slightly longer than the estimate.