Not sure if this is in 308 AR or NFA category but....

The old OTB suppressor for the 24" SR-25 EMR, the one that screws in at the gas block.

Does anyone still make one? If not how hard are they to track down? If tracked down how much?

Not in a big hurry to get one (if at all) but genuinely curious and thus far I can find no info or even a proper name.

Thanks