This is the new push lock breech plug. It has a different internal thread to accept the new push lock fitting. The push lock fitting will hold standard shock tube without any insert, straight fitting, or ferrule nut. It has the ability to hold the shock tube and then release when the operator pushes on a release ring. This new plug uses a different firing pin and spring. It can also use the original firing pin and spring and any combination of the new pin, spring or old pin and spring. Call Scott Johns for more details.