Rex Silentium Polonium-30 (Black). Budget-friendly .30 caliber rifle suppressor with 1.375x24 HUB threads for your choice of mounting system. Handles full-auto from short barrel 5.56 rifles up to .300 RUM and .300 Norma Mag. External weight reduction design sheds heat faster. Built-in internal and external flash hider for superior flash reduction with night vision. Includes 5/8x24 direct thread adapter and tube clamp. 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