Hello Ace
Friend, I know of (3) “Lasers”.
1) The one you’re talking about, I believe Titan has. It clips onto the vertical post of an airless machine. Aim it out in front of the gun, right onto your snapped chalk line. Some buy (2). The second is aimed straight down below the gun to designate where to start and where to stop. ( Where to pull the trigger and when to let go. )
2) The other is a unit that bolts on the handle bars. It shows a beam that is aimed at a box, perhaps 96′ away, perhaps 156′ away. The idea here is that if the beam is inside the target box, and you begin spraying, and, while moving forward, you keep the laser inside that target box, the line will be straight. You’ll need to look down to know when you start and stop spraying.
3) This other laser is a variation of the 2nd. It swivels. When your striper dips into a swale, this laser will swivel, remaining vertical.