4" Inner Diameter DirectVent Pro Galvanized 30° Elbow Use to offset obstructions as needed. Fully unitized, twist-lock construction. Elbows swivel, allowing the lock to remain fully engaged while aligning to the desired direction. The angle will remain fixed at 30°. DirectVent Pro features tight inner connections for superb performance, with no gaskets or sealants required (unless specified by the appliance manufacturer). Low-profile locks and no hems or beads allow for a beautiful product that looks elegant in any interior. DirectVent Pro is a unitized, coaxial venting system designed for use with direct vent gas or propane stoves, heaters, and fireplaces. Features: Inner Diameter: 4" Outside Diameter: 6-5/8" Angle: 30° Looking for Simpson Dura-Vent? You found it! Simpson Dura-Vent has changed their name to DuraVent. DuraVent is a recognized technological leader in the venting industry. Consistently the first to market with new innovations in venting systems, DuraVent has captured a leadership position in emerging markets. DuraVent has patents for several products and continues to design safe and technologically advanced venting. The company's research into solving problems with corrosion, when biofuels such as corn are used, led to the break-through patent for PelletVent Pro. Scientifically proven materials and unequalled engineering make DuraVent products not only the best choice, or safest choice, but the only choice for professional quality venting products.