When shooting round steel targets it is advantageous to have a round rear sight. The circular plate fills the arc of the sight to make for easy target acquisition. The Eagle Eye Peep Sight drops into a wide variety of Williams Gun Sight Co. fiber optic sights for added flexibility. This easy to use upgrade allows the shooter to intuitively center the front sight in the aperture, resulting in clear and faster front sight focus. Easy drop-in installation and instinctive sight centering. The sight supports access and utilization of rear windage and elevation controls. It is made from CNC machined aluminum for long lasting durability. The Eagle Eye Peep Sight is anodized matte black to absorb light and reduce glare. The new ghost ring style peep sight fits Ruger® MKIV and MKIV 22/45™ pistols. NOTE: This product requires a compatible Williams Fire Sight to be installed with a removable elevation control and U-shaped rear fiber optic. The Eagle Eye is installed by backing out the windage adjustment screw, removing the rear fiber optic and replacing the piece with the Eagle Eye Peep Sight. Fits the Ruger® MKIII™ 22/45™ LITE and Ruger® MKIV™ 22/45™ LITE with the #12940 Williams sight installed. The Eagle Eye sight is made from CNC machined 6061-T6 aluminum with a black anodized finish. It is approximately 0.65" W x 0.3" L x 0.5" H and weighs 0.1 oz. Made in the USA by TandemKross.