This is a simple 14mm CCW thread adapter for the Cyma CM.127 AEP.
The CM.127 has a glued piece of plastic at the end of the barrel where a 14mm CCW thread “should've” been.
As such, I modeled this thread adapter with an extra cover piece to protect the threads when no supressor / tracer is attached.
To install, simply use an exacto knife to pry out the glued piece of plastic and then secure the thread adapter with 2 tiny drops of cyanoacrylate glue.
The author marked this model as their own original creation.