The aluminum j-arm adapter is a must have for helmet mounting but is still not the way to go for weapons mounting. The aluminum mount does give the ENVIS housing a fighting chance but the plastic housing is just to soft for it to be sufficient for recoil induced stresses. The adapter is great but not enough in of itself to be a mounting interface for weapons use.
The ENVIS's plastic housing may be soft and weak but its core is rock solid, stronger than most monoculars. The components making up the core are all aluminum, reference the picture below.
The most rigid and structurally sound way to weapons mount the ENVIS is with the Alamo Four Star DLOC QD Weapons Mount. The polyetherimide polymer that constitutes the OEM infinity focus stop ring is more than strong enough for mounting the DLOC and for handling any recoil induced stress forces. Of course if desired an aluminum or titanium ring could easily be installed making a nearly fail proof interface. The infinity focus stop ring on the ENVIS is located underneath the tapered rubber cover, just aft of the objectives slotted sleeve.
Lights, Lasers, Mounts & Accessories : DLOC-PVS