The Osprey family of suppressors has pistons that are easily changeable for different host weapons or subcalibers. Pistons are constructed from 17-4 stainless steel and then heat treated for maximum durability. The piston is part of the Nielsen device that moves and allows semi-automatic cycling, but it also contains the female threads that attach to the muzzle of the host pistol or sub-gun. These pistons are easily interchangeable for compatibly with all relevant host guns and can be changed out to be compatible with subcaliber host guns, which means you can shoot smaller caliber rounds through the same suppressor, making it a multi- caliber silencer.
Starting with the new SWR Octane HD 2 in 2012, the Octane suppressor now uses the same piston as the Osprey. So, if you have a new Octane, this is the piston you need.
If, on the other hand, you have a 2011 model Octane or Octane HD, you will need the old Octane piston.