How laser rangefinder work?

[V for Vendetta]

I play arcade and my laser rangefinder doesn't work, is there an option to set the key or is working only in realistic battle?

[The King of Spades]

It doesn't work in arcade ground bc your tank already does it with that green aim thing. It's for ground RB and SB.

[V for Vendetta]

Thanks

[Nomad]

You need to set a key but in Arcade Mode is irrelevant because you know the distance of the target automatically.
In realistic mode you need to press the button to active the laser range finder and in one second the laser gives you the distance you are aiming and correct the range.