Precision-machined, buckhorn, rear sight and base include screws that fit the holes in your Wesson & Harrington rifle for drop-on, no gunsmithing installation. Slider has a detent that lets you feel each adjustment; setscrew locks into place. Ladder has side markings so you can easily repeat the right yardage settings. Drift adjustable for windage; setscrew locks your setting. SPECS: Machined steel, blued finish. Sight - Ladder has approximately 1-27?64' (3.6cm) height adjustment; Buckhorn aperture 5?16' (8mm) I.D. Base - 19?64' (7.5mm) high from bottom of receiver to top of base, 2ѕ' (7cm) long, 5?8' (15.9mm) wide.