Dead Air Sierra-5 (Xeno mount). Dedicated 5.56 silencer built for professional use. Welded Stellite baffles in a stainless steel outer tube for proven durability. HUB compatible (1.375-24) mounting. Compact footprint with minimal weight. Balanced sound and flash suppression. Knurled design for function and form. Note: If this product is reflected as in-stock it means it's either physically in-stock or allocated and available (serial number is assigned) at my distributor