Diamondhead?s revolutionary D-45 Integrated Sighting System takes sighting to a new level. If a fast, accurate CQC target acquisition is needed or the optic goes down, simply flip out the D-45 Sights and roll the firearm 45 degrees counter-clockwise. The D-45 Rear Sight?s patented Diamond-shaped apertures and Diamond-shaped upper housing allow the eye to place the D-45 Front Sight?s post in the exact center of the Rear Sight?s aperture. The spring-loaded D-45 deploys with the push of a button and stows flat..