This "glint killer" is a real gift for those who wish to remain undetected. It has certain qualities that make it unique in the art of stealth. It has the equivalence of a 4 inch "shade" tube and keeps the objective lens from being detected. "Butler Creek" caps work just fine with this unit and it comes with different thread spacings for NXS and Benchrest scopes etc. It does not change the "dope" of your scope and protects your objective lens. Highly recomended by units of our Special Forces. Just another great addition for those who take "stealth" seriously. Remaining undetected improves your advantage. You are a "ghost" when they can't see you, hear you, feel you or smell you. J.D.