Lancer Tactical
If you're running a 3-hole FAST helmet and want a single NVG clip mounted without the wobble of an ad-hoc rail, the Lancer Tactical 3-Hole NVG Shroud is the simplest fix.
It bolts onto the standard 3-hole pattern used by most FAST-style helmets — 3B, FAST SF, and their clones — and gives the clip a solid aluminum base to attach to. No extra plates, no aftermarket shroud hunt. The hardware is included in the box, and you're typically looking at a couple of hex keys for the install.
It's a straightforward aluminum block, black finish, so it sits dark and doesn't flash under NVG or daylight. The universal fit works on virtually any 3-hole FAST variant on the market, though if your helmet has a non-standard mounting surface or a modified plate pattern, a dry-fit check before committing is worth ten seconds.
One NVG clip only. If you're running dual tubes or want both sides available, you'd need the dual-version instead.