The lifetime-warrantied Chim-A-Lator damper-cap is operated by a lever, on the right side of the firebox.  This lever gives 6 positions of draft control / heat retention.  The damper/cap mounts directly to the flue tile just like a single-flue cap, requiring at least 1 1/4" of tile above the crown.  The damper/cap is 11" tall and comes with a 30' cable and a 7'   cable shield to protect at rub points.  A 50' cable is available.  Larger sizes are available special order.