The XPS series of sights from EOTech are the shortest sights from EOTech to date which leaves you with more rail space than other EOTech sights. With the popularity of the 300 Blackout, EOTech integrated a custom Blackout/Whistper BDC reticle designed for the balistics of the 300 AAC Blackout cartridge. This smaller sight runs on a single CR123A battery which provides a life of up to 600 hours. Having a shorter sight allows for more room to mount detachable iron sights for backup, or to mount any other accessories you might want. EOTech XPS sights feature an integral mount for use on Picatinny or Weaver-style rails.