Just want to share what I discovered: from Turbo the light steps down to High on 2 min timer.
But it also has a thermal step down: after 2 min turbo without cooling the light gets fairly hot when it steps-down - if I bring it back to Turbo, it steps down again after a few seconds. Doing that when the light is fan-cooled brings another 2 min of turbo.
With 519a and light diffusion foil this is quite a useful headlamp.
