I initially thought it was an expensive and unnecessary gimmick too until I tried a pair of NL's with and without. But £105! Nah.I might mention that while initially I thought the forehead rest for the NL's was a gimmick - I now use it, and I like it a lot mostly because it helps me get good eye position quickly.
But careful negotiaton tactics, comprising a rapid about-turn and a brisk walk towards the exit door, had the desired effect and lo and behold, they were added FOC.
Absolutely brilliant bit of kit which transforms this old gits 10x42's!