Forward Controls Design SIG MCX Enhanced Magazine Release Button Black. EMR-MCX will not work on TDP spec AR15s/M16s. Forward Controls Design used the same proven and successful EMR curved and horizontally serrated surface on the EMR-MCX as well with the same self centering and vertical movement mitigation features. Forward Controls Design's not fans of flat control surfaces a simple (but expensive to machine) curve does wonders for the AR15/M16 spec EMR button. Combined with effective horizontal serrations the design auto centers the user's finger and mitigate vertical movement of the finger. The distinctive curved and serrated surface is helpful in identifying the magazine release button without a visual in an otherwise flat and featureless receiver surface. The curved surface does even more for EMR-MCX as SIG MCX's magazine release button is much longer than TDP magazine release buttons. Machined from 4140 steel and black nitrided EMR-MCX is compatible with SIG rifles that use the elongated magazine release button such as MCX M400 Switchblade M400 SDI XSeries and SIG716. Specifications for Forward Controls Design SIG MCX Enhanced Magazine Release Button: Manufacturer: Forward Controls Design Gun Make: SIG Sauer Gun Model: SIG Sauer MCX Color: Black Finish: QPQ Fabric/Material: 4140 Steel Package Contents: Forward Controls Design SIG MCX Enhanced Magazine Release Button What firearm models does the manufacturer say Forward Controls Design SIG MCX Enhanced Magazine Release Button is compatible with? The manufacturer says that Forward Controls Design SIG MCX Enhanced Magazine Release Button is compatible with SIG Sauer MCXForward Controls Design EMR-MCX: SIG MCX Enhanced Magazine Release Button Black