The FGA SACL portion is machined from a polymer (Delrin). The fasteners and index pin are phosphated to Mil Spec STD 171. The FGA was not designed for the waterproof storage of articles, but items can be stowed inside the central core. The FGA’s primary mission is to be used as a front grip, and not to store batteries etc. The FGA was designed for rapid on/off with a solid interface that could withstand the massive heat generated by modern small arms. The aluminum rail interface eliminates the compression set and subsequent loosening problems associated with a plastic coupling. The FGA is not rail sensitive, meaning that the FGA can be installed on any rail within specification (Mil-Std 1913).