Teamed with a Lyman receiver sight, this low silhouette front sight provides precise accuracy on the range. Designed for use with dovetail slot mounting, they are supplied with seven interchangeable inserts that are locked into place with a threaded cap. 3/8" dovetail. Measured from bottom of dovetail to center of aperture.  Machined from one piece of steel for durability and longevity. Available in four heights: .404" No. 5017AHB, .494" No. 5017AMI, .584" No. 5017AUG, .852" No. 5017ATC