The Rugged Sub9 provides an ideal compact short and quiet package at 6.8 inches. Designed for full-auto durability, tuned specifically for 9mm PCCs and SMG platforms. Compatible with HK Spec 3 Lugs and HUB 1.375x24 systems. Rugged's Universal 3 Lug Mount provides stronger and more concentric lock up. Also universally threaded for additional mounting systems. Caliber: Pistol calibers up to 9mm, 300BLK Subsonic, .357mag/.38special, 350 Legend. 1.73 inch diameter, 14.1oz with mount. 17-4 Stainless body, Hard Coat Anodized Aluminum Front Cap, High Temp Cerakote finish. 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