DuraVent DVL 6" Diameter x 40" to 68" Telescoping Double Wall Black Stove PipeThe DuraVent DVL 6" diameter by 40" 68" telescoping length of double wall black stove pipe adds between 38. 75" and 66. 75" of length (after connection) to the stove pipe run. DVL double wall stove pipe can not be cut to length so the telescoping length makes installation simple with no cutting or crimping necessary. For example, if you're installing a wood burning stove and plan to go through the wall with the chimney, you might need a telescoping