BLF A6 Switch Question

I am considering an A6 since it comes with a warm emitter option... but my question is, what is the "forward and backward mode" switch?

Does it have a momentary function?

If not, is there a switch that can be swapped to provide momentary activation?

No momentary. I'm not sure about swapping it out but I'm sure it's possible. It may screw up the UI though...probably not something you would want to mess with.

It's a reverse clicky, with a catch. Full click for on. Then a quick half press = next brighter mode as you would expect. But a slightly longer half-press/hold/release = the next lower mode. So you can go up or down in brightness without turning it off. Pretty nice!

The switch is neat. mark6 nails it. But a different way of saying it:

It basically has a Reverse feature, if you will. So say you full click the light on, first mode is Moon mode, you can then longer half press and drop back to Turbo. I basically say it rocks into Turbo. It is really slick.

Full press and click turns on.
Quick tap goes forward through modes.
Longer press reverse through modes.

These other guys have got it right on, but I'll add that momentary activation is a feature found on forward clicky switches - switches that engage their mechanism at the bottom of their travel. Press it slightly and it comes on, press it all the way and it locks on. The A6 has a reverse clicky switch. The power circuit is completed when the switch comes back up into its resting position, after engaging.

Both styles have their merits - forward clicky allows momentary because you can turn the light on without locking it, reverse clicky is much more handy for swapping modes because you can "momentarily turn it off" to trigger the mode change, without unlocking it.