Trickle Vent Air Box Comfort Extra fast installation-There is no need to drill a window !!! 100 pcs 

Recommended for windows opening forward !

Restores ventilation in rooms to prevent condensation and mold formation.

-fits to be installed to any plastic profile

-no need to open the window to ventilate the room

-no street noise and air drafts

-Manual adjustment of air feed volume

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-Note!  The installation of the window vent flapper does not require changes in profile. There is no need to drill a window!!! 

You are welcome to watch a video instruction!

The principle of functioning:

Fresh air from outside enters the channel between the frame and the sash in place of replacement of a fragment from typical seal to a special one.

Then the air goes through a valve mounted on top of the flap and enters the room.