This is a single NON-Vision detent. Customization with added performance is what its all about. ND new Impulse style threaded ball detents with custom star milling. Our detents have a slightly higher spring rate. This helps prevent double feeding when using force feed hoppers. Yet, not that strong to create unwanted wear on the detents or bolt. Custom milled profile Slightly higher spring rate. Helps prevent double feeding when using force feed hoppers.