Threaded extension screw eliminates excess movement of the magazine release button on AR-10® and AR Heavys (.308) magazine release assemblies. When installed, the extender lengthens the shaft and positively secures the magazine release button to the threaded shaft of the magazine catch. The magazine release button will set out further from the receiver giving the user an improved, positive release. Even if you don't use it for an Ambi-Catch™ installation, this inexpensive part will improve the fit and function of your standard magazine catch. Requires a 3/32" Allen (Hex) wrench to install.