The RUSH features a compact head and Black Gold's pin-brightness-managing Photo Chromatic shell. High performance Photo Chromatic shell is 80% tougher and changes color even faster Interchangeable fluorescent sight ring for quick and positive peep alignment even in low light. Brighter, Stronger pins. Photo Chromatic™ Technology. Unmatched Adjustability. Unbeatable durability. Undeniable innovation. Unconditional guarantee.