This has fail written all over it.
Just like a few years ago the guy selling thread adapters for pop bottles. You don't see them any more either.
The legal definition of a silencer is anything that is used to muffle the sound of a shot is a silencer.
The thread adapter part that he is registering as a silencer, is not going to suppress the sound therefore, technically could not be classified (legally) as a silencer even though he is treating it as such and by doing so, he is putting numerous legitimate silencer manufacturer thread adapters and any other barrel attachment in legal peril.
Each and every individual component used in a silencer to muffle the report is a part of that silencer and cannot be replaced or repaired except by licensed manufacturers. The only exception that I know of is a wipe. Which is very old school technology and is a solid piece of rubber that fits inside the silencer tube body at the end that the bullet passes through. An oil filter is much more than a solid piece of round rubber and there is no way that will continue to pass the scrutiny of tech branch for long.
Coincidentally, wipes are well known in the silencer community to cause for a very innacurrate gun. And I'm not even going to discuss exactly how in the hell this guy is going to use any type of sights other than "instinctive shooting" which is nothing more than a wild guess.
Also, silencer owners cannot have any spare parts, and cannot repair their own silencers.
So, if the buyer ever threads an oil filter onto this thread adapter, or uses another oil filter than the one that came on it (if it does in fact come with an oil filter) or even possess an oil filter that will thread to this adapter, it will be considered as more than 1 silencer and thus, the owner will be in violation.
Trust me, you don't want any part of this train wreck. If you are wanting a silencer, by all means, buy a real one, but this one is not it. This is worse than shade tree.
Just for the sake of conversation, let's say you theoretically (illegally) did screw an oil filter onto this thread adapter and thus made a silencer, how long do you think this is going to last before the muzzle blast and heat and lead build up kills it? You gonna get your money's worth out of the paper media before it catches on fire
Because you can't just replace the oil filter when it does wear out. Legally, only licensed manufacturers can do that.
And just look at all the things you're physically shooting through.
This is double face palm stupid.