I have the Sight Light SL-100.
I've tried others. The stupid bullet looking ones stink. The SL-100 is the only one that has reasonable accurate and repeatable results. I haven't used the scope leveling bit yet. I test it a few times. Remove the leveler and retest a couple times. But it allmost allways gives repeatble results.
I have sighted in four AR's, 2 with a scope, others with Irons and 1x red dot or both. 3 Glocks I replaced sights on. And 2 Kimbers I replaced sights on.
It's a pain sighting in AR's that have a scope, 1x, and irons. 3 times the fun. This allows me to get all of those really close before I even hit the range.
I also used it to verify that my Dan Wesson Valor was shooting a bit low before I decided to swap the front sight. Wasnt sure if it was me or the pistol until I put the laser in. Someone else shot that pistol dead on, while I was allways low.
It has allways got me on paper at 25 yards with the rifles. Close enough to make sure my mounts were on good and close enough to make final sighting in a breeze. With my pistols, it's results are nearly allways the same as what I see at the range at 10-15 yards.
It's great fo making sure the sights are lined up right on Glocks and Kahrs. Shooters new to those often shoot low and left. But the laser shows them that thier gun is fine, it's their fingers problem.