Gem-Tech PISTON-GM45-1/2-28 GM-45 and Blackside-45 LID Piston Core 1/2-28 An extra LID Piston Core allows you to easily change threads on a GM-45 or BLACKSIDE-45 to use one suppressor on either U.S. standard threaded pistols (0.578-28) or with European (Metric) threaded pistols. Not only does the pistons let you use your suppressor on your .45 suppressor but with our other options you can also use them on 40 caliber and 9mm pistols. All options can be installed in the field without the use of tools. 9mm 1/2-28 (for using a GM-45 or Blackside-45 on 9mm handguns)