BCM upper receiver gas blocks

What type/brand gas blocks do they use? Set screw, clamp, taper pin?

RECCE type set ups; we have our own made.
Looks much like a PRI, Troy, YHM etc…

dimple, set screw, degrease, high temp loc-tite.

Exposed gas blocks, the same as above, plus taper pinned.
Exposed gas blocks (all Mk12 models) are all VLTOR gas blocks.