Nederlands 
How much lower does my glass get with a trickle vent?
That is the vent's glass deduction. It differs per vent and is listed with every vent. With a glass deduction of 80 mm, a pane of 1000 mm high becomes 920 mm.
If you order new double glazing from us, enter the height minus the glass deduction in the configurator; the width stays the same.
