Oakley M Frame and sod the cost.
, I now buy several pairs of Bolle safety sunglasses for about £6 a pair and chuck them when they get damaged. No issues with them under a helmet though these days I have the sun visor built into the helmet which is brilliant.

Photo chromatic ( transitions) pin lock insert is the way to go
If you're a brown eyed Johnny, they may well work adequately, but having pale blue eyes, no photochromatic lenses or pinlocks I've ever tried go near enough dark for me.
I wear sunglasses even on days when the sun isn't out, as glare makes me blind......on bright days, I'm squinting with my sunnies on AND my helmet tinted visor down.
The upside is that I can see very well in the dark though![]()