Lego minifig compatible Custom SI-Dan Toys PVS14 Night Vision Goggles, clip onto all SI-Dan Toys Helmets that have a rail at the front like the M2002, PT202, BK-1X, IBH, IBHG, ACH, PBH and HGU.

The excellent thing about the PVS14 is that you don't have to unclip it to move it all the way down.