Not as much as i expected. It’s about the same height as the bottom of the window of an Eotech exps 2. It barely blocks a tiny amount of the field of view if mounted directly in front of the sight but the further forward you mount it on the hand guard, the more it will block your view because of the angle of the bottom of your your line of sight. It’s low enough to use back up irons over it, but i am going to use a riser for my Eotech so it doesn’t interfere with my field of view at all.