The Improved Tang Sight's quick-release post system makes it easy to replace the post that came with your sight with a higher or lower one for targeting at different ranges.Choose a lower post for close-in targets or a taller post for longer ranges. Post height is also click adjustable for fine-tuning when sighting in; each click represents ¼" of adjustment at 100 yards. A jam nut locks the elevation, so you can remove and reinstall a post without losing settings. Mfg: Marble Arms SPECS: Steel, blued. Heights measured from base of post to center of aperture. Standard - 1.341" to 1.876 height adjustment range. 1/2" aperture disc with .055" peep.