Two SilencerCo pistons. One brand new 1/2"x28XL (works on all standard barrels, but especially effective on Beretta M9/92FS handguns when using an Osprey. And one 13mm LH piston for factory Sig Sauer threaded barrels, used slightly, but chemically cleaned, and scrubbed after each use. $70 each, or I'll make a deal on both.
From the manufacturer:
The handgun suppressors have pistons that are easily changed 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 compatibility 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.
These pistons are compatible with the following suppressors:
Omega K series