Can be used in vertical and horizontal installations. Internal spacing bead assures uniform insulating air space between pipe walls.Highlights:Easy to useHighly durable4" inch, 4VP-90 Degree, Elbow, Type L Pellet Vent3" inch clearance to combustiblesInner wall is constructed from stainless steel and the outer wall is paintable galvanizedRolled-over male end eliminates sharp edgesRated for flu temperatures up to 570 degrees F