Slides over the muzzle and around the post sight, this barrel thread adapter is matt black alloy with grub screws and alan key for fixing to barrel, plus knurled thread protector. Designer to allow the use of moderators and muzzle brakes. 1) Marlin 60 19″ barrel a) 1/2″-28 thread Bottom part of the adapter has been contoured to clear the magazine tube. 2) Marlin 795 a) 1/2-20 thread b) 1/2-28 thread