PelletVent is a complete venting system from DuraVent for stoves and inserts that use oil fuel or multi-fuels (including wood pellets, corn, cherry pits, switch grass, coffee husks, walnut shells, soybeans, wheat, sunflower hulls, rapeseed and sugar beets). The 4 in. Wall Thimble adjusts to fit most walls and is designed for high-altitude installations or installations over 15 ft. high. With a sleek black interior side, the wall thimble blends easily with most interior spaces. For added durability, PelletVent seams are factory-sealed on all elbows, tees and fittings.