It will fit Aether Helmets. Bought 2 Aether helmets & 1 light. I would not fit on my wife's helmet but would fit on mine with a loud click. the defect is in the Rock Lok system. Hers is a few millimeters thinner than mine. So upon another reviewer's review he Velcro'd the light to the Rock Lok 5. I did the same.
The Giro Aether has Roc-loc 5 but it is apparently a different (light) version of it and this light does not fit securely. I love the idea so I am actually using Velcro to attach it to the helmet, at least until the days get longer.
This is a nice light but it only truly fits the Roc Loc 5 that has the soft rubbery adjusting wheel. My Roc Loc 5 has the hard plastic adjusting wheel and I had to use two zip ties to tie it to it�s intended location. Just check your adjusting wheel on your Roc Loc.
I bought this light because it was compatible with my Giro Helmet. However, the first one I received proved to be defective and I had to return it for exchange. The replacement has worked well so far, but we'll see how it is over time.
