Electra with IRID lenses: what it is and what it does
Long story short: IRID lenses get darker and lighter according to the surrounding light, in less than 1 second.
They are like photochromic lenses, but perfectly instantaneous
They don't have any battery. Not even a small one, not even a solar one. Zero.
They cover the whole range that goes from 17% to 42% of transmission of visible light (VLT), so they go from being an S3 lens, to almost an S1 lens, covering pretty much all the conditions that you can find in the mountains.
So you can simply ski, and let IRID take care of all the rest.