The Effikal/E EMD series manual damper is a multi-purpose damper designed to reduce flow through a vent pipe or other ductwork. This damper can be used to enhance the performance of a boiler, control heat delivery, or to reduce the sound of an appliance. No electrical connections are needed. The damper is constructed of aluminized sleel, with a stainless steel version available. The damper may be installed on the flue outlet of an appliance or down stream in the vent pipe. The adjustable index plate is easily accessible and located on the exterior of the damper. The index plate allows for ten adjustments from the fully open to the fully closed. Once the damper blade is adjusted, it is locked in place by the use ot the index plate stopping any fluctuation of the blade.