Strike Industries AR Advanced Receiver Extension AR Style Mil-Spec 7075 T6 Aluminum Flat Dark Earth. The Strike Industries Advanced Receiver Extension updates aesthetics and functionality for the AR15/AR10 platform. Scalloped surfaces reduce friction with tight fitting stocks and help shave weight while retaining mass in critical stressed areas. Type: Extension Tube. Model: AR Style. Size: Mil-Spec. Material: 7075 T6 Aluminum. Finish: Flat Dark Earth. Country of Manufacture: No. Manufacturer: Strike Industries. Mfg. Part Number: ARARET7FDE.