Product Description MCX VIRTUS UPPER ASSEMBLY - 9" 300BLK Complete 9" upper assembly kit for your MCX Virtus in 300BLK. DETAILS SIG SAUER MCX Virtus Upper Assembly. Convert your AR15 to the SIG SAUER Virtus. Complete with upper assembly, stock adapter kit and match duo trigger kit. Specification Model - SIG MCX Barrel Length - 9 in Caliber - 300 Blk