Selkirk has introduced the Metalbestos Model MDV Direct-Vent Chimney System. The MDV provides corrosion protection and minimal leakage due to an inner stainless steel liner. MDV also contains a specially engineered woven fiberglass seal for a more secure connection, and a LockTab feature that locks the edges in place. These locked sections can then be rotated 360 degrees, making offset installations of this system easier. MDV can be used for both sidewall and conventional through-the-roof venting. Selkirk.