Rugged and precise sights, machined to hug the receiver for lowest line of sight, least protrusion. Audible-click, A 1/4" minute adjustments for elevation and windage. Elevation slide is scribed in 3 minute increments. Quick release allows slide to be removed with a press of a button. Elevation stop screw permits instantaneous return to zero. Mfg: Lyman SPECS: Aluminum, black, anodized. Comes with two apertures, A 1/2" (12.7mm) x .093" (2.3mm) and 5/8" (15.8mm) x .040" (1.1mm). Model 66 WB fits Winchester 1886 Win. & Browning.