Who is the maker on this M16 helmet?

[norwest]

ET66? I can't quite make out the letters before the 66. Thoughts?

[MAP]

Looks like ET to me.

This may not be 100% correct but there were only a few "German" manufactures that made size 66 helmets during WW1 (or at least observed).

ET, Q, Si, TJ, KM and W

Austrian makers also made 66's but the one shown is not Austrian.

[norwest]

Good information, MAP. Thank you!