I have 17 yrs experience servicing mostly the 400 series ALPHAs.
Our own manuals derived from the HISL ones, said that to glue velcro on the helmet for NVG packs etc, we were to use ADOS F3, and never F2. F3 is simply a thicker version with much less solvents in it. The reason given was possible softening of the shell if we used the high solvent version.