just to reiterate , and add a bit
The very first proteus goggles had the strap mounted on the back of the ear piece ( like the current ones ). These strap mountings were breaking and dropping masks. Available only in black. I think!!
They revised this by attaching the strap through the ear piece attchments and carry on to the lens frames ( like normal spectra 260 / flex 7 etc ). That way , it could n't fall off. Again just in black at first.
The newer ones came with the shorter strap ( again attached at the back of the ear piece ) new colours and the flexi rubber chin bits.
They do seem to have more of a tendancey to fog up though!! Even with the fan ( one of the guys has the fan , and still fogs ). Not just me that has found this. The whole team noticed it.
The ear piece rotated on all of the models.
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