I would say any of these silencers are pretty much an inch or two of foam surrounding the inside of a tube , apart from the airflex which seems to be silencing by sheer length .
I have a mytee silencer which I stick onto the back of the enforcer, its pretty crude in construction though , u can be sure the Ashby's is really well made and probably performs better than most , so I'd say its worth the price in the long run.