The Yankee Hill Machine QDS Flip Up Sight System features a spring loaded deployment system that automatically flips the sight up at the push of a button. Front and rear sights lock positively in the folded and deployed positions and are precision machined from high strength aircraft aluminum and hardcoated to military specifications. FeaturesFront sight available with either standard or hooded (HK style) stem Front sight is standard handguard height Rear sight has a dual peep (A2 style) aperture Front sight folded height: .435" Rear sight folded height: .435"