Truglo's Rimfire Fiber Optic front sight fits most Ruger MKII, MKIII, 22/45 and Browning Buck Mark Rimfire Pistols. Its easy to install and is extremely bright in low-light conditions. Replaces factory front sight. Replaces factory sight. Fiber Diameter: 0.060". Front Sight Height: 0.445". Fits Ruger MKII, MKIII, MKIV, 22/45, and Browning BuckMark, rimfire pistols. *Please note: Not suited for use with Marlin hood front sight models. Not suited for use with Ruger tapered barrel designs or 22/45 LITE models. Does not fit BuckMark contour models.