The Laser 3Dot is described in the game as:
Uses three lasers for fast target acquisition.
This can be found in western Mojocoyo in a cartel outpost. There’s a large cartel presence here, as you’d expect, with sniper towers and an alarm. The accessory case is upstairs in a building in the corner of the outpost with a cartel lieutenant.
This is definitely easiest to approach at night, as I did. I started with the snipers first as always, followed by the alarm, then moved through only taking out anybody directly in my way to keep a low profile. If that’s your goal too, you’ll want to use a suppressed handgun for maximum furtiveness. At night, the men in the building should be asleep, which helps.
The three lasers are meant to improve accuracy, but I do find them slightly distracting. I guess it makes you look a bit like the Predator though, which could be cool.
I do equip this on my LMG load out mainly for shooting down helicopters. While at that range it doesn’t provide a direct benefit, the practical use is increased aim stats to help stay on target. But I honestly don’t know if it really does any good.