Forward Controls Design Low Profile Duty Magazine Catch Black. LMC was not designed for large frame ARs the shorter shaft feature is designed with AR15/M16 width lower receivers in mind. The winterizing feature similarly only works on AR15/M16 lower receivers. How much thought can one put into an AR15/M16 non-ambi mag catch? A lot. LMC is based on the development of the EMR-A (Enhanced Magazine Release Ambidextrous) and is centered around mitigating accidental / unintended magazine drops. NOTE: LMC is designed for TDP spec M16s and AR15s. None of LMC's features are beneficial on large frame AR style lower receivers. 308 AR spec mag catch shaft is longer LMC's is shorter than TDP spec in order to lower the magazine release button's installed height. The winterized feature is wildly inconsistent on 308 ARs to the point of that feature being useless due to the varying dimensions of large frame ARs. The longer catch on the plate is lengthened from TDP spec and doesn't apply to 308 ARs. In short do not use LMC on large frame or 308 ARs. Specifications for Forward Controls Design Low Profile Duty Magazine Catch: Manufacturer: Forward Controls Design Gun Make: AR Platform Gun Model: M16 AR-15 Color: Black Finish: Nitride Fabric/Material: 4140 Steel Features of Forward Controls Design Low Profile Duty Magazine Catch 0.01in longer catch (LMC's 0.06in vs. TDP's 0.05in length) that engages the magazine's catch cutout window Shorter (by 1 full turn of the magazine catch) shaft that lowers the installed height of TDP spec magazine release button on the right side of the lower Winterized design to mitigate water pooling in wet and freezing temperatures Package Contents: Forward Controls Design Low Profile Duty Magazine Catch What firearm models does the manufacturer say Forward Controls Design Low Profile Duty Magazine Catch is compatible with? The manufacturer says that Forward Controls Design Low Profile Duty Magazine Catch is compatible with AR-15 M16Forward Controls Design LMC: Low Profile Duty Magazine Catch Black